Feeling like you don't have an out is tough. I know there was a point when my paruresis got so bad I was having trouble even in my own home. I would think "What if I can never go?" and then would imagine the resulting trip to the hospital. I would eventually calm down and I never did have a situation where I actually had to go to the hospital, but I know the feeling of panic that sets in once you start thinking along those lines. The thing that helped for me was to realise that panic is only temporary. Anxiety is like a Chinese finger trap in that the harder you try to fight it, the worse it gets. So don't fight it. Allow yourself to feel anxious/panicky and wait until it naturally subsides on it's own. A panic attack is not physically dangerous. The other thing that helped is I made a firm decision that if I ever felt it necessary to actually go to the hospital, then I would go ahead and go to the hospital. This took a lot of the pressure off me.

Short of going to the hospital, for paruretics there are a couple of options that can give a guaranteed "out". The first one is a catheter. I don't know if there's such a thing as an anal catheter but I've had a colonoscopy before so I do know it's possible to have a tube up in there. It would probably have to be combined with an enema/laxative of some sort. A medical doctor would probably have a better idea of what can be done in that regard.

The other option is what is called the "breath hold". Unfortunately it doesn't work for everyone, and it may require some practice to be able to hold your breath long enough, but if it does work it's a lifesaver. There is a state called "hypoxia" in which a lack of oxygen in the bodily tissues results in the automatic relaxing of the smooth muscle tissue, and hence incontinence. The idea behind the breath hold is to try to deliberately induce hypoxia. Some who have trouble holding their breath have reported that breathing into a paper bag can have the same result.

Out of curiosity, have you spoken with a doctor about parcopresis? You could show him this website to prove it's validity. You should let him know that it's causing you to be unable to go even in your own home so he understands how serious it is.