Fever for 3 days??

Ok so my son is 3 months old today and has had a low grade fever, on and off, for 3 days. It has ranged between 99.0°F and 99.9°F. His pediatrician and I have talked and given his other symptoms (excessive drooling, fussing during feedings, chewing on LITERALLY everything, etc.) we decided he is teething. But is it normal for it to come and go for 3 or more days? And is it normal for him to go from a normal temperature, 98.6°F, to a low fever and back multiple times in a day? And should I be giving him tylenol? I know it's not a real fever till it hits 100.4°F but I just dont know, I dont like that it's been going on for 3 days now.