Onset of sudden tenderness in the back of the head....HELP

I got decompression surgery in June 2012, I had shunt surgery on December 13, 2012, My shunt surgery involved putting a shunt in the syrinx and having it drained to right outside the syrnix back into the spinal area..... Anyways, the last few days, my neck has seem more tender then normal at the incision spot, and I woke up this morning with it hurting up more at base of my brain where my shunt surgery hadn't taken place. No stiff neck, but extrememly tender, small headache I think will be building today... any suggestions? Most of it is just on one side...no unusal bumps or leaks that I can feel.

Thanks