Most likely a growth spurt. I wouldn't worry about it too much.. As long as he hasn't run a fever therefor he is lethargic. Call Ur pediatrician if Ur really concerned. U should be going in anyway soon for Ur 1 month-Wellness check. Bcuz he's older he drinks more milk at a single feeding vs when he was one wk old-etc. when his stomach was smaller & would drink 1/2 oz every 2 hrs. Ur baby will sleep in longer stretches also. Instead of nursing every 2/3 hrs it may be more like every 4 hrs. But u should always feel free to call Ur pediatrician with any concerns. I know I did with my 1st baby...
I'm just wondering is it a growth spurt? Is It normal? He usually is awake awake lot during the day