chances of a concussion?

I know this is probably silly especially because I'm an EMT and already know this stuff but being a first time mom I'm still freaking out a little bit and would love some feedback. my son is 5.5 months and was sitting up but fell backward and hit his head on the floor. he was on his play mat on top if very thick faux fur rug on a wood floor. he cried for about a minute but stoppes as soon as I gave him his bink. it seemed like it was a pain cry at first then turned into more of a scared cry. he's acting fussy but it's also naptime. right now he's laying on my chest sleeping. I'm afraid to leave him alone. what do you think? should i take him to the doctor today or tomorrow even if he has no signs or symptoms of a concussion? or just wait and see. I don't think he has a concussion but there's that little part of me that's always afraid of the worst happening.