Handbanging on walls and biting

[abreacti0n]

Many times when i get really angry and/or sad, i bang my hand on the wall really hard. My hand has now become swollen and it hurts touching it, i also bite my hand or dig my nails into the skin.

I'm starting to do this stuff more often and worse each time, how can i stop???

[My_Hero]

That's self harm right there, and can only progress to worse stages. I started out with biting my hand, or digging my nails into my skin; that lead to cutting. A dark road you don't want to go down.
Try some non-harmful alternatives for when you're feeling angry or sad. Write it out, break something (I used to take like, 15 pencils and break them all into tiny pieces when I was pissed. It helped, and it didn't hurt me.), listen to loud angry music; anything but hurting yourself.