Thank you for the query.
Sometimes skin rashes can be a first symptom of inflammatory bowels disease (like Crohn`s disease). And so can have your friend especially that he has lost weight recently and have digestive tract symptoms like nausea
. If he also suffers from blood in stool
, mucus in stool or diarrheas, this is quite probable. I suggest you to visit gastroenterologist and consider colonoscopy
Hope this will help.