It has been mentioned here, and it could be any number of things, not to mention some, including Prednisone(if you were taking it).

Factors that can contribute to GERD:

Hiatal hernia, which increases the likelihood of GERD due to mechanical and motility factors.
Obesity: increasing body mass index is associated with more severe GERD. In a large series of 2000 patients with symptomatic reflux disease, it has been shown that 13 % of changes in esophageal acid exposure is attributable to changes in body mass index.
Zollinger-Ellison syndrome, which can be present with increased gastric acidity due to gastrin production.
Hypercalcemia, which can increase gastrin production, leading to increased acidity.
Scleroderma and systemic sclerosis, which can feature esophageal dysmotility.
The use of medicines such as prednisolone

To help you:

GERD is largely preventable through changes in lifestyle, which are also used as treatment (see below).

"Sleep on the left side, or with your upper body raised.
Relief is often found by raising the head of the bed, raising the upper body with pillows, or sleeping sitting up.[20] The upper body must be raised, not just the head; pillows that only raise the head do little for heartburn and put strain on the neck. Sleeping on the left side also keeps gravity working for you, keeping your stomach below your esophagus.[21]
Eat smaller meals.
Eating a big meal causes excess stomach acid production, so attacks can be minimized by eating smaller meals. It is also important to avoid eating shortly before bedtime.[12]

Lose weight.
Gaining even a few pounds increases your risk of heartburn.[20] Exactly why isn't clear, but the leading theory is that more body fat puts more pressure on the stomach, which can cause highly acidic stomach contents to reflux to the lower esophageal sphincter. For the same reason, tight clothing around the abdomen can also increase the risk of heartburn.

Avoid acidic and rich foods.
Though less well supported by evidence,[20] a sufferer may benefit from avoiding foods that trigger their symptoms. These commonly include acidic fruit or juices, fatty foods, coffee, tea, onions, peppermint, chocolate, especially shortly before bedtime."

http://en.wikipedia.org/wiki/Gastroesophageal_reflux_disease

Be very careful with GERDS. I thought, well, it's miserable but one of those things you just live with. You don't eat after 7 pm. You don't drink things like orange juice or fatty things. What I didn't know is that it can be a dangerous disease. I had no idea that I was bleeding in my throat until I ended up in the hospital, I could have bled to death. My hemadrycate (spelling) was half, my white blood count was thru the roof, they figure as a reaction to the trama to the body. I had to have a spinal tap to rule out Lukemia or an infection. All from GR\URDS. My point is just to be careful. I have wondered since then if that trauma to the body could have brought the MG out because of the predisposition I already had. I take prilosec that is perscription. It is much cheaper that way, according to your insurance. Also when if flares I put the bed up, luckily we have an adjustable one, or if it gets bad (coming up thru my nose) I go out on the recliner so as to not wake my husband up. It make make you cough pretty bad. And I have had pnuemonia twice from asperating it. my point is it can be scary stuff. It's not just heartburn. Carla

Hi! Yip it seems to be really common wih us myasthenics. The meds definately don't help especially the pred and the mestinon which are both very corrosive. Are you on anything to stop acid,lke nexiam or losec? The food getting stuck in the throat thing culd mean you have weakened swallow. It happens to lots of us who have bulbar symptoms. Really hope it gets better!