Crying all the time.

FTM here and my son just turned 4 weeks. At first he slept all day and night and barely cried except to feed and change. Now the last almost 2 weeks he cries all day long and we can't put him down or he gets hysterical. He barely sleeps during the day anymore, maybe a couple hours total, and wants to eat nonstop. He is super gassy so we've been giving him the drops and also switched from Similac Advance to Similac Sensitive but there's been no change. Nothing soothes him. He'll fall asleep in my arms but the minute I put him down he wakes. He screams his head off and not sure if something is wrong or if this is normal. Doctor keeps telling me this is what newborns do but I think his crying is excessive. Is anyone else dealing with this???