Having diarrhea after antibiotics
is not rare, but also not normal. I recommend you to have stool test
for C-diff and
for occult blood.
Having problems with breathing is probably from the acid coming up into your throat and then down into lungs. You should fix this promptly, it may damage your lungs (aspiration pneumonia, with lung scars).
There's another possibility - alergy to one of antibiotics. Would you say you have any lips or face swelling or skin itching?