Tell me about it. I've lost count of the times I've sat in the doctor's surgery, in a meeting, at a friend's house, on a bus/train, even in my meditation class (which is supposed to relax me!) - in fact, any time i'm in a room with other people for any length of time - going blue in the face trying to control the agonising gas.
The worst is when everyone knows you've already escaped to the bathroom twice, you come back and sit down just for it to start again....no more excuses. I can feel the anxiety rising just thinking about it.