Could I possibly have a concussion (I doubt it)?

Well, it's pretty late to ask, but yesterday I was doing something and then I was coming out of the underside of one of those playground things (don't ask), stood up to early, hit the metal bar really hard and made a really loud sound from the hit. I was on the ground for about 30 seconds, developed a fairly large goose egg, was slightly lethargic (though I got up and walked home after), slightly nauseous (though I got hungry after like 10 min) and had a slight headache (a tiny one, not a legit headache. I put ice (well compacted snow, same deal) on the bump for the 25 min it took for me to walk home, symptoms persisted for about 20 min.

You don't need to say that I shouldn't sleep, I already did (because I was an idiot). I feel no symptoms today.

Just a quick check.