What Causes Fever, Strep Throat, Nausea And Weight Loss?

I am concerned about a colleague. She is ~35 yo professional female who also has 4 kids. She now weighs 85 lbs at 5 6 , and told me she was sick most of the past year (past 8 months). She often has fever, just now it was with strep throat but there were many other reasons (some surely brought from day care by one of her kids). She says whenever she feels sick, she also feels nauseated and can only eat very little, which is why she lost weight this year (from around 95-100 lbs). I asked if she takes vitamins and she answers she would probably be dead if she had not taken daily multivitamins. Any underlying disease?