Baby Fell and hit his Head?

My 3 month old [on april 11th] i left him sitting on the couch while i went to grab his bottle in his room and as i thought about it it happened he scooted of the couch and landed on the floor [carpet] landed on his back and hit his head he started crying he i comforted him until he was ok we gave him his bottle since it was time for him to eat went out to the store and kept him awak for an hour then we just couldnt keep him awake he wanted to sleep and no matter what we did he stayed asleep what should i do? he woke up in lest than 20 minutes and is in his crib right now talking to him self and hes really responsive im just worried i dont know i feel so guilty i just want to cry i always thought id never let that happen. what should i do and what signs should i look for i called his doctor who then told me to call some other number that doesnt have any one there until tommorow morning please help