Is bactrim (sulfamethoxazole and trimethoprim) good in treating stomach ache?

Please, no!: Bactrim (sulfamethoxazole and trimethoprim) is an antibiotic and would only be useful for treating a specific infection caused by a bacteria sensitive to this drug. The indiscriminate use of antibiotics has led to the development of drug-resistant bacteria that are causing life-threatening infections. Furthermore, taking antibiotics can kill "good" bacteria in our gut, leading to the overgrowth of bad ones. Put down the bactrim!

No: Stomach aches aren't usually caused by bacterial infections.