Possible concussion?

When I get really stressed out or angry I tend to bite or hit myself really hard on the head. After particularly insane math homework I banged my fist as hard as I possibly could on my head 5-7 times and then used my iPad to hit my head 3-4 times. I've had a very sensitive forhead and have noticed the slightest touch puts my head in pain and that I've been extremely sleepy as well as unable to do my math as I keep mixing up numbers and adding numbers that were never there. This happened on Tuesday and it's Friday with no sign of my head not hurting and Ive starting to mix up things like sentences instead of just numbers while reading.
Added (1). I can't tell my parents without explaining how it happened and I have full plans for the next three days and don't know what to do

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