C.B.
Hi,
I went through this. I carried around a small emtpy juice bottle with a screw top for any emergency. Great on buses, planes etc. you can go into the bathroom and just use bottle instead of tiolet, dump and rinse. The other thing that was a huge help was this folding seat.
http://www.pottytrainingconcepts.com/Cushie-Traveler.html
It really did the trick.
After a while, my son just got over it. I suggest you don't worry or make a big fuss over it. He'll know when he's ready.
Oh and don't forget to feel very fortunate to have a child who learned toileting so easily! I had that experience too, it was great, and a little fear of strange toilets is probably nothining compared to what some parents have to go through.
All the best,
C.