Pee shy?

klgallup

My son has been potty trained for a few months now. Everything has gone pretty well except he will not go out in public. At first I thought it wasa fear of the big potty but I have tried both a potette and bringing our potty from home. He happily sits on the potty but he clenches his knees together and won't go. He has yet to have an accident in public. He just holds it until he gets home. The other day he held it until 3 pm (he had gone first thing in the morning)! It can't be comfortable for him holding all day and I worry that he is going to be upset if he has a public accident. Any suggestions? He seems to be OK in other people's homes. Just not willing to go at a public venue.