over your head
over (one's) head
1. Too complicated to be understood by one or someone else. My jokes always seem to go over Stephanie's head, so I'm glad you think I'm funny at least. A lot of this technical stuff is way over my head.
2. Bypassing one's or someone else's authority. She just wouldn't listen to me, so I had to go over her head to her boss and complain about it.
3. Lingering in one's mind as a source of concern or worry. All these bills are hanging over my head, and I don't get paid for another week. I'm so glad that exam is over—it's been over my head for months.