Potty Training- Fear of Public Restrooms

I think since your son has just made the transition from diapers (which he was used to for 3+ years?) to the home toilet (less than 6 months?) that you should continue to let him go at his own pace. It sounds like you are acknowledging his fear, which is good, and it's something that will likely fade over time as you gradually support him through it. In the mean time, what about a small portable plastic molded potty & letting him use it in the car? Here are a few possibilities if that idea appeals to you both:
http://www.theecstore.com/index.php?main_page=index&c...
http://www.lullabyebaby.com/juvenile_sol/travel_potty_sea...

Big transitions like going from diapers for 3 yrs to underwear and using the potty are tough for toddlers & preschoolers who get really used to routine. I think it's important that he be given time to make the transition from home toilet to public toilet, and in the mean time just make it a non-issue by providing him an alternative that he feels safe using. Years from now when you look back, this fear of public restrooms will likely just be a tiny blip on the radar. What's far more important is that he's no longer peeing/pooping in the diaper!

Will he go at someone else's home, like grandma's house? Maybe you could try staying all night there to get him used to going someplace else, or even a hotel for the weekend. Maybe if he has no other choice he'll do it and realize it's not a big deal.

This won't work everywhere --- but what about taking in a training potty for him to use at the daycare. It would be his special potty. He shouldn't be holding it all day-- he'll get a bladder infection.

ahhh... I know what the root cause of this one is. I had to go through it with my two year old and then again with my five year old. (My five year old is the one who explained it to me)

It stems from the fact that most public restrooms have gone to auto-flushing toilets. (So most kids think any toilet that isn't their home potty is an auto-flusher.) Kids are so small that if they wiggle at all, the auto sensor goes off. The resulting flush while they are still on the toilet is scary and uncomfortable.

When you take them to a public restroom, make a big show about covering the auto sensor (even if there isn't one) with your hand or a bandana, and reassure them that it won't flush until they are ready for it to flush.

This worked for both of my kids.

I am a mother of 3 children. I have a 10 year old son, 6 year old daughter and 19 month old son. I am going to have go through the potty training again soon...ahhh! I trained both of my other two children on the toliet in my house. I never used a potty chair becase I did not want them to get used to it. I think you should get rid of the potty chair and have his use the toliet in your bathroom and then he will be used to using a regular toliet.

Best of luck.