jesse,,,,

If you hit the towel rack hard enough to cause a concussion, you would have damaged the towel rack.

It takes 60 Gs to cause a concussion.

Could you stand on or hang you body from the towel rack? No, it would come off the wall.

The sharp corner triggered a lot of nerve pain from the nerves in the skin. The startle triggered anxiety that brought on all of your symptoms.

The fact that you tried to mimic the hit and bruised your arm suggests you are wrapped in anxiety. That is an OCD reaction.

The bruises have no bearing on concussive forces.

Please seek help with your anxiety. CBT to teach you a new thought pattern after a head bump would be beneficial.

My best to you.