This could be a case of occipital neuralgia. This usually happens due to spinal nerve compression because of upper cervical spinal nerves caused by overuse of computers, work involving straining of neck, herniated disc, canal stenosis, bone disease, spondylosis, poor posture. You should have a MRI focusing only on C1-3 and also look at C1-2 instability. Another possibility is a boil or abscess. So feel around and see if you can feel a lump. Do discuss this with your doctor and get yourself examined. Take care!
Since this is something that started recently---within the last couple of months---and I've already been diagnosed with spinal stenosis in the lower spine, hip region, I'll keep it in mind.
Tho't I might have a brain tumor... Glad to know that's probably not it.
(Don't have health insurance right now, but once I do, if it continues to bother me, I'll have it checked out.)