"There is something wrong with you."
|with you right but who not| |Mit dir stimmt doch was nicht|
I don't see how I'm supposed to get 'there is something wrong with you' from that.
I'm interested, how you managed to get 16th level in German. No offence, I'm genuinely intrigued.
As for your question, here's my uneducated opinion: 1. stimmt <- stimmen. It's a verb. 2. was = etwas (in this case).