My Dog Has A Hematoma On His Ear It Is Not Bleeding Or Anything Should I Just Leave It Go...

It's always best to have the vet look at it... It could probably wait until your dogs next visit though.

A hematoma in the ear usually happens because the dog is shaking its head--it either hits its ear against something or shakes so violently that a blood vessel inside the ear breaks. The bleeding continues until enough pressure builds up to stop it.
If nothing is done for it, the swelling will eventually go down, but the ear will look thick and shriveled. You also need to find out what is going on inside the ear that caused the head shaking.