Possible concussion?

Well today I went to play paintball, all in all it was fun but one shot was point blank (less than 6 feet away) directly to the back-of-the-top of my head. After the headache went away five minutes later I thought nothing of it but, seven hours later here I am, I poked it trying to figure out where it was and I felt something odd.

I instantly felt light-headed, blood rushed to the surface of my eyes; identical to the feeling when you are about to black out.  As suddenly as it happened it went away and I'm fine now aside from some slight dizziness, I am unsure whether to poke it again to check for a similar reaction or leave it alone but, I'm inclined to do the latter.

I'm not usually an alarmist and usually if it happens once and never again I don't worry about it but, this is just so unusual I had to ask someone. If I can't sleep I'll go to a doctor either way but, any opinions will be appreciated.