Hi, I would get checked if you get sudden onset of these symptoms : Fever (high such as 101 or 102 F) headache, stiff neck, and vomiting and nausea. There are other symptoms like confusion, seizures, change in smell or taste, loss of balance and sensitivity to light. A fever of 99 is usually normal. You can get other things from fresh water like parasites (Giardia) and so forth. So if you get diarrhea and things like that you can get tested for stool parasites. So if you develop bad diarrhea stomach cramps etc. Then see a doctor for that.