get yourself some acidophillus to restore good flora to your intestines while on the abx (antibiotic), I am glad you are on some - and going to another dentist
If you have any pain, tell him - tell him what you need and what you are feeling. you are paying him to treat you.
I doubt the new dentist will say anything - watch for facial expressions as you tell him what was done to your mouth. other dentists don't put other dentists down - it's scary out there. they get scared and we end up with pain.
keep us updated please!