I recently had chickenpox and now have a mild to moderate but persistent headache, should i return to my doctor?

Yes: Chickenpox can cause inflammation of your brain. Your headache may be a different source but be checked. All the best.

Yes ...: A rare but possible complication of chicken pox is encephalitis (inflammation of tha brain). For more information see http://patient.info/health/encephalitis-leaflet. From your description it may be relatively mild, but formal review and consideration of investigation / treatment important.

Probably to be safe: A headache after a viral infection is quite common and is most likely not dangerous. A more serious cause could be from meningitis or encephalitis but this is unlikely if all you have is a mild headache without any other features like nausea/vomiting, the light bothering your eyes, drowsiness, confusion or change in behaviour. If the headache is worrying you then you should get yourself checked.