Usually i get diarrhea after drinking milk. but if i eat one clove of garlic along with milk, i never have the problem (diarrhea). lactose intolerance?

Not sure : Interesting association you have found. I'm not sure how the garlic is helping. Can you eat cheese ? Yogurt ? Without garlic? If not , just try lactaid (100%) milk without garlic and see result.

Odd...: Happens if drink milk as part of a meal? Food affects stomach emptying, which affects digestion of lactose load. Possible eating garlic affects stomach emptying too.