Gotta agree about probiotics; Consumer reports did a study and found most didn't live up to their ad. I started taking the yogurt starter in the stores- it works great! Since I had been using it to actually make yogurt, I knew it had plenty of probiotic action.
You might take probiotics during the Antibiotics when the damage is being done; why wait until after when it's already out of control? Nip it in the bud.
Does your dr believe the Acne is caused by the gut bacteria, or is the Acne improvement just a happy by-product of the antibiotic?