6 week old wont eat!

Erin

Hi ladies. My son who has been nursing like a champ is suddenly refusing to eat. He ate a good feed about 1030am. Ever since he will latch for a min or 2 then scream and pull off. He will take a pace and fall asleep. I've tries a bottle (which he normally doesnt like) he took .5oz. I pumped a bit to make sure there was milk in there and there was. I haven't had any supply issues. He seems uncomfortable so we gave him gas drops. Hes currently sleeping. What should I do? Any suggestions? I'm starting to get nervous. At what point would u call the doctor?