Ear temp 37.8, underarm under 37. doc recorded forehead at 38.2. feel fatigued, especially in afternoon. no soar throat or runny nose. just tired. going on for 4 days now, worse in afternoon. what could this be?

Low grade: It's too soon to regard this as a fever of unknown origin and start a complicated battery of tests. Your temperature is very borderline high with 37 being average. If you don't improve after a few days, a battery of tests, like cbc and differential, mononucleosis test, liver enzymes, urinalysis with microscopic examination, urine culture and blood culture would be recommended. Nonspecific now.