I went to Mexico with 3 friends. I was on antibiotics. They were not. I was not affected. They had severe diarrhea, no fever, larthargic, irritable, stomache pains, muscle pains. I gave my boyfriend, the heaviest, probiotics right away and he seemed better within 24 hours. The other 2 were sick for a few days. The tiniest, my best friend, is still experiencing diarrhea and now is complaining of chest pain. I was the only one that didn t get sick. Could this a bacterial infection that s moved to her lungs. We were swimming and she was complaining of swimmers ear at one point. Also, would Cephanllexin help her?