I just recently started having this kind of pain. I'm not sure if it's exactly the same. It doesn't hurt necessarily to pee, but as I'm going I have this pelvic pain and feel like my muscles around my bladder are just spasming. It's very uncomfortable.

Does that sound the same?

Mine comes and goes and seems to be worse in the morning or if I wait too long to go. As far as I know, I've never had endo around my bladder, but I know I'm having more endo symptoms and facing another surgery. I'm thinking this may be a new issue.

Haven't found anything to help, but I'm interested in what others may have to say as well. Hope it was an isolated event for you.

You should see a Dr. to make sure its not a UTI or something you need antibiotics for, its really important to treat infections, I had a transvaginal infection, and the Dr. gave me metrogel, and I forgot to take it because I had my period, and I was so sick, and like 3 days later, I felt like I broke my back and ended up in the ER. (oops)
It could also be scar tissue from endo/surgery, it could be endo, and also a disease highly associated with endo; intercistial Cystitis- "Interstitial Cystitis (commonly abbreviated to "IC") is a urinary bladder disease of unknown cause characterised by pelvic and intense bladder pain, urinary frequency (as often as every 10 minutes), and pain with urination. It is not unusual for patients to experience nocturia and pain with sexual intercourse. IC is also known as painful bladder syndrome (PBS),". Got that from DS.
Something to maybe look into, I have IC and endo as well, and was told that the endo and IC are called the "evil stepsisters" because a lot of us with endo have IC.
For the symptoms, drink tons of water, like down it, and I add cranberry juice in (not the cranberry cocktail, I get the real cranberry juice, and just top off the water), and I down (not sip) like 2- 3 huge glasses at a time, and hold in my pee, and then when i finally really have to go, it helps. There are also cranberry pills you can take that work OTC.
Feel better, and I hope this is just an isolated issue, not ongoing!

I do have pain when I go, but it's more like wildorchid mentions, where it hurts when I let my bladder get too full and then hurts after my bladder empties, as the muscles readjust (just my interpretation of how it feels). Intense pain like you're talking about sounds more like a UTI or bladder infection. Those are really easy to clear up, but I would definitely have your doctor run a pee test.

I had this pain too after my fertility treatments. I guess all the estrogen I was pumping in my body had to have flared something up. I changed my diet, I no longer eat gluten and very little meat. You're supposed to cut out sugar too but I cheat a little (or alot). I found it has helped TONS!!! I have no more bladder pain or discomfort.