You must be taking Good Probiotics if your taking Antibiotics. I took Doxy for almost 2 years and always had stomach issues. I stopped after throwing up blood. I just tried to take it again and my body said no way.
Make sure you always eat something with it too and take the probitics at least 2 houes before or 2 hours later. I try to wake up in the middle of the night to take my probiotics.
I also just bought a product called yeast away it is probiotics with a extra enzyme in it that really attacks yeast. I hope it works for me my friend benifited so much from it.
Good Luck, I hope your tummy feels better soon.