Antibiotics can cause some problems with your digestive tract. Most commonly, they kill off the "good" bacteria in the intestines and allow the "bad" bacteria to get a foothold. A common infection that results is one with clostridium difficile. This can cause severe diarrhea, abdominal pain and blood in the stool.
Your symptoms also sound as if you may have gastritis or an ulcer. It may be worth being tested for H. Pylori (a bacteria that can cause these things).
One other thought would be that the throat problem and your current symptoms may be related but not due to the antibiotics. Crohn's disease can sometimes present like this, although your presentation would not be "classic" for Crohn's.
If you are not getting better you may need to see a GI specialist.
Follow up with your doctor is important.
Advice and opinions given are based on the information provided and must not be considered an official medical recommendation. The limitations of the internet prevent an appropriate evaluation. Always consult your doctor if there is concern.