baby eating less

So i took my 2 month old to the doctors the other day because he’s been pretty congested. He said that his lungs sound beautiful and to keep doing saline, humidifier etc. since yesterday he’s been eating a bit less, taking him a while to even get down a few oz and then he falls asleep mid feed which isn’t like him. should i take him back to the doctors or is this normal? I also have been monitoring him for a fever and he hasn’t had one.