hi, headaches 2 yrs after the surgery may not be related to the earlier lesion.Please consult Neurosurgeon and get yourself examined again(repeat CT scan).
Do you feel dizzy?.Any history of nausea or vomiting since last week?
Headaches are observed after subdural hematoma sugery .
http://www.nlm.nih.gov/medlineplus/ency/article/000713.htm
But it is better to meet up with your surgeon who operated for furthur evaluation