You could be having stress headaches, take a couple of paracetamol and see if they help.I had a friend who had similar problem and believe it or not it was tied to stress. Do you having anything stressful going on presently that could be contributing to the problem? I suggest you Home remedies for headache through this you get instant of knowledge about How do you get rid of a headache .
Unless if you have history of stroke, it might be. But why not consider headache, maybe a migraine?
Get a CT scan ASAP. Don't wait. Do it to make sure its nothing serious. Don't wait. It could be a clot or several clots trying to form. Go to be safe. God Bless.