Hi,
How are you? If there was no trauma to the head or neck, this could be caused by primary headaches such as migraine or cluster headaches. Migraine usually presents with one-sided headaches and may also be associated with nausea, vomiting, sensitivity to light or sound and even numbness in the case of hemiplegic migraines. Rest, ice pack, avoidance of triggers and prescription medications may help. If it persists, it is best that you see your doctor for proper evaluation. A complete neurological examination and direct clinical examination will help with the diagnosis. Take care and do keep us posted.
i should also add the headache is slowly getting worse.