Azithromycin - very bad stomach cramping and gas for 3 and a half hours?

I have had no trouble on the past taking this but this week since I've been on it the cramping is unbearable feels like a belly full of gas

Antibiotics are indiscriminant in that they kill both good and bad bacterias. there are good or beneficial bacterial flora in the gut that keeps the digestive system working correctly and antibiotics kill this flora too. The best way to combat this is with probiotics like lactobacillus and Acidophilus. These good bacterias can be found in yogurts, buttermilk, and in commercial probiotics like Culturelle. Try to eat one or two yogurts with live cultures or take a commercial probiotic as directed on the package and this will help these unpleasant GI side effects of abx.