What Can Cause Numbness After Indentation Post Laminectomy?

I have an indentation that just started a little afte one year post laminectomy l4 l5 fusion. It is the size of a nickle and about 1/2 deep so far. Is this dangerous? What is causing this? My surgery left me with more pain post surgery in the lower back and above the laminectomy and numbness and pain in calves and right foot. Can't walk more than a short block and now I think I have a fever an bowel infections. Any answers?