yes. no matter u use armpit or ear thermometer, 37.8 is consider fever but mild one. did he had any vaccine taken b4 his fever? if no, since he is only 3 mth old, i think better bring him to a pd. =)
usually i will use wet hanky to wipe ds's body n forehead when he is having fever, aft tt stick a fever patch on his forehead. and rmb to use lukewarm (or room temp) water, dont use cold water =)