 [ Symptoms ] what can cause pain in the lower right abdomin my daughter was diagnosed with a severe case of strep and mono last weekend the strep is gone or should say doctor says her throat looks a lot better but the mono is not she is complaining of pain her glands of her neck both sides and she has said for the last few days she has had pain at night and sometimes during the day in her lower right abdomin she is on an antibiotic it is the penicillin v 500 mg 2 x day i know that causes diarreaha but is this serious should i have her looked at again [ Disease ] two basic possibilities a food poisoning or what is sometimes called stomach flu and b some more lasting problem either way you need to stay hydrated and go see a doctor