This is my first post and I will do my best to not write a book. I have been reading posts on here for over a year (learned a lot) but never initiated one. As you can tell from my name "still not sure" I am questioning if I have MG or something else. I am female and was 51 yrs old when my sx started suddenly in Sept 2015 after vacationing at a beach; with a feeling of my jaw hanging open, a pressure feeling in the back of my neck/head which would worsen when lifting and bending over to put something in a lower cabinet, etc., heavy head, swallowing felt loud/more pronounced, excess saliva, food & pills were at times hard to swallow and would cough/or felt like going down the wrong pipe.  Symptoms would improve when I reclined on the couch.  I would feel normal when I first woke up in the a.m. but then syptoms would start after an hour or 2. I have a history of TMJ so my doctor thought it was TMJ acting up. I had recently had a tooth filling replaced, started wearing glasses for computer monitor and reading, and was seeing a chiropractor for weight loss and upper back issues (he reset my hyoid bone a day or 2 before symptoms). Also rode a jet ski with my adult daughter, with a lot of bouncing and jarring on the waves. So, right from the beginning there were so many possibilities that were causing my symptoms. Since TMJ was at the top of the list, I spent the next 10 months receiving TMJ treatment with a mouth appliance 24/7 except when eating. Over that time my symptoms became less intense but were still there and I began to get a fluctuating heavy feeling in my upper arms. After seeing a few specialists for neck problems, I finally saw a neurologist who suspected MG (Nov 2016). Had the basic normal work up for MG (MRI Brain and antibody tests-all negative). I was referred to a neuromuscular neurologist at a large teaching hospital in the DC area. At that time (April 2017), I had noticed my right eyelid and right side of face looked a little droopy in photos. Had Musk antibody test, EMG, RNS, and swallowing study-all negative. Finally had the single fiber EMG which was mildly abnormal at the frontalis muscle (above eye); the EDC muscle (forearm) had no abnormal individual readings but the mean jitter was mildly increased. In June 2017, working dx was seronegative MG. Then had breating test (PFS) which read "Normal TLC; reduced FRC, RV, RV/TLC Ratio. Neuro said the results were very good-no need to worry about breathing issues.  Started Mestinon-which made the pressure/weak feeling in the back of the neck worse and had major stomach side effects; tried Mestinon several different times over the next 6 months (also took Levsin with it). My normal day was working full time then come home and eat, get things ready for the next day, then collapse on the couch for the rest of the evening.  Jan 2018 tried to start exercising, new years resolution, (stationary bike and freestride trainer). I noticed my eyelids would start to droop about 6-8 minutes in (the right much worse than left) and my mouth would start to hang open, just felt really physically exhausted afterwards but would recover rather quickly. Saw neuro again in Jan 18, (showed her pics of my eyelids after exercise) but she backed off the MG diagnosis somewhat- said it was possible that I had a mild restricted form effecting the eye muscles only, but did not think the other symptoms were MG. I asked about the SFEMG results in the arm showing increase in mean jitter and she said that was too broad of a statement and she did not think it was generalized (she was the one who performed all 3 EMGs). Stopped Mestinon completely for the next couple of months. Back to neuro at the end of March 2018; my eyelids were having symptoms during the visit so she was able to see it for herself.  She then said, we are suspecting that you might have a generalized problem but we haven't completely confirmed that yet; not sure if all symptoms are related or separate issues. Based on her clinical exam, she did not find increasing weakness in the body compared to prior visits, even though I currently feel like I have fluctuating neck and arm weakness with various tasks (doing laundry, washing hands, looking up at high shelves in stores, and fluctuates while at work (desk job). I have never experienced not being able to lift arms or my muscles giving out, but I do drop things frequently.  Again, not sure if MG symptoms? Neuro suggested I try the Mestinon again about 30 minutes before exercise and could occasionally (no more than 2 x per week) use red eye drops that contain "naphazoline". She said it helps open the eye.  I tried the eyedrops and yes it helped but can only use sparingly. She insisted she is not starting me on a steroid or steroid sparing med at this time since she is not certain if generalized (which I am grateful that she hasnt after reading about all of the side effects). I have not had a chest CT-she did not think necessary.   Yesterday I got the nerve up to try Mestinon again (took it 40 mins prior to workout) - it worked great!!!!!! My eyelids hardly drooped at all after a 26 minute stationary bike ride and I did not have that all over physically exhausted feeling-Yay!  After about 2 to 2.5 hours I started to feel the neck/arm symptoms which lasted about 20-35 minutes and then subsided (could that be rebound weakness?). This was the first time that I have had a definitive positive response from taking Mestinon.  I don't go back to the neuro until September 2018, unless my symptoms worsen, then I should go back sooner.  So, I am still not sure if MG or not? I know any responses will not be medical advise, only individual's sharing their own experiences. Has anyone had similar symptoms or a similar experience on their way to diagnosis?  I know sometimes it can take years to get a definite diagnosis especially if seronegative or a mild form or ocular only. Sorry post is so long.  Any repsonses will be very much appreciated.