What Causes Headache And Nausea?

I had Viral Meningitis 6 months ago. I has in the hospital for four days. It took me a while to start getting energy back but it get better. I had the headaches and nausea for a while after. I went my doctor because I didn t fell completely better after 4 months athough my headaches and nausea were down to 3-4 days a week. He gave me a lower grade pain killer than I left the hospital with because I didn t want an addiction problem on top of my other issue. I only took them when a really needed. My doctor told me to just wait because a full recovery from meningitis can take a while. The symtoms seemed to be getter better but...I followed up last week because now I am back to constant headaches and nausea every day for the past 3 weeks or so. It starts about 20 minutes after I wake. Usually Nausea fist then the headache but not always. He gave me a migrane meds that need increased over the next two weeks. He also ordered a MRI. I have it on Friday. Q: Is there something else that could be going on? If so, what? Can it really be taking this long to get over meningitis? Could the meningitis have cause other complications?