My husband and I went backpacking 12K feet and he becasme sick 1 day into it. We are avid backpackers and outdoorsmen/women. he has had sever diarrhea for 5 days, lost 6 pounds, can not eat, has sever bloating and movement in his stomach, some nausea, has fainted once, yesterday, and is not getting better. We thought maybe giardia (sp) but not sure that is it. His diarrhea is with force and is all water. Even when he drinks water he gets sever diarrhea. He only had vomiting the first day. Please help.