My Son Started Taking Clarythromycin Today As Perscribed By His

My son started taking Clarythromycin today as perscribed by his college nurse. He has very bad nausea and some vomitting during his college Lacrosse practice. The team trainer sent him home from practice at which time he started having severe watery diarreah. which has continued. He is drinking pedialite to stay hydrated. His trainer told him to continue taking the medicine as perscribed and to not take any over the counter meds to stop the diarreah.