What sort of probiotics did you use? It's important to check out the delivery system. If you use veggie capsules, or powders, only about 4% of the good bugs make it through the stomach acid. If you use a BIO-tract delivery system, about 60% make it through. Similarly, it's important to pick a multi-strain probiotic. Antibiotics really wipe out the diversity of gut flora, so in replenishing it, you want to get as many strains as possible. I'm a big fan of LoveBug Probiotics' Here's the Skinny; it really works for me, but you'll have to figure out what works best with your body. Most importantly, probiotics aren't just a response to antibiotics. Stanford published a study showing that bypass patients taking probiotic supplements post surgery lost about 10% more weight on average than patients only relying on probiotics in their food, and also had higher B-12 levels. TL;DR try a different probiotic, and stick with it long-term!