I hate the phrase just have to let it pass and the word monitor

My son has had diarrhea since saturday and has no appetite. According to the Dr. we have to do the two things above. I feel like I'm just waiting to have to take my son to the hospital for dehydration. Just wish this bug would go away! Hydrating this kid as much as possible and his poor hiney is raw. Using aquaphor now to try and protect it