This is Dr. David
you need to consult a GI doctor and get more testing.
you could develop new allergies or sensitivities to certain foods such as lactose sugar in milk or casein protein in milk, or gluten wheat protein in pasta, pizza, and breads.
new bowel allergies to certian foods or oils in your diet can cause bloating, gas, constipation
new irritable bowel syndrome can be caused by IBS or irritable bowel syndrome as well.
are you willing to see a GI specialist and get more testing to find out what might be wrong?
wellbutrin can cause abdominal pains, diarrhea, increase gas and flatulence as common side effects after taking it for 2 months.
another option is to taper off of the wellbutrin and see if your symptoms get better.
if they get better, then it was the wellbutrin causing the problems.