I've had two concussions, both from football. They hurt less the more you get them, and become less noticeable.
My first one I got knee'd in the back of the helmet on a fumble return. Everything was purple, I lied down on the sideline, and I'm not gonna lie, I shed a tear. I couldn't look at light, and went into my bedroom and just lied there. That one sucked.
Last one I got hit head on, stinger right down my neck, and just was bad for like 15 minutes, but a concussion nonetheless.
If it hurts a little bit when you shake your head, have trouble remembering common facts (address, phone number, where you're at, age, etc.) shortly after the accident are pretty good indicators, as are sensitivity to light and loud noise.
Go to primecare if you're covered, and ask them to check you out. You have to do a twenty question questionnaire, then you're diagnosed.
But seriously, GET THE FUCK CHECKED OUT. Because concussions are like the Wu-tang clan. They ain't to be fucked with. And they get less noticeable. But vibes to you for wearing a can. Shows you're smart.