I could only lie on my right side when I was very poorly, not on my back and defiantly not on my left. It didn't make me feel like going to the loo, but the inflammation pressing on sensitive parts hurt a lot. As the inflammation has reduced I can lay anyway now, which helps a lot for cuddles in bed. Hope you get sorted soon.
Crabby I used to have terrible trouble with my bladder; I think it is common for people with IBD.
I used to get up to go in the night a lot and in the morning I would have what I called morning cystitis, literally dancing around cos I need to pee and dreadful burning, that went away slowly during the day. I found that taking cranberry extract tablets has all but eliminated it. I take one at night and one in the morning, no more dancing and no more interrupted sleep. Hope that helps.