D.H.
K. ~
I can't really help much with the potty training part, but have a suggestion.
The next time your son is sick, ask the doctor to write for the chewable antibiotics. My son used to get the diarrhea from the liquid antibiotics, but not with the chewables. I don't know why they never write for them, but someone did once for my son and after that I always had to ask specifically. My son said they tasted like the "pink medicine."
D.