Sorry about your son having mono. I don't understand why he can't take Tylenol. I know it can affect your liver in large doses but I took 6 mp for several months and have been taking the maximum dose of arthritis strength Tylenol for years with no problem with my liver - I have it tested often. But then temp of 100 is not serious and hope he is getting gradually better. I remember one can really be tired for a long time.
ElaineNY