I was in Costa Rica and I think I may have picked up an intestinal parasite. Looking at the symptoms, I have them, diarrhea, lack of appetite, upset stomach. It started 4 days ago. I haven t eaten much the past 3 days and am thinking that may be why my stomach hurts. I loaded up on Imodium and pepto to make the 12 hour trip home, so the diarrhea has slacked off. How long should I wait to see a doctor, if the symptoms persist?