I am hearing little popping noises/creaking doorsin my head i had Skull Fracture Surgery on March 17th 2010Surgery.

I had head surgery in March 2010, I been hearing little pops where the surgery was done. I used to hear creaking noises in the same spot along with my popping noises. I went to the Docs & they said they never heard of that happening.. My incident was a blood clot behind my ear, I fell off a fence.. I was 17 when it happened, I am 18 now. & still hearing the popping sounds, it started again after a couple months..Any idea why i'm hearing this? Please respond, Thanks.