I used to play dominion mainly and got pretty good at it but got sick of all the OP champs and went to classic for a while. Today i went back to dominion and felt like a complete noob and its like i have forgotten how to play. Lol what happened?

Your just out of practice and not use to the drastic itemization changes that have occurred recently in dominion as well as other slight changes such as the aura, ect.

I certainly hope so i don't think i was even that bad when i started around level 10 so i didn't have much LoL experience..... at all