What could cause chronic headache? tension headache almost 3 months no relief, vision blurry, nausea, mri/ mra/ ct/ blood work normal. nsaids dont help. what to do next??

You should see a neurologist who specializes in headaches. There are different kinds of headaches (like tension headaches, migraines, etc.) and the treatments for the different headaches are different. The fact that you have blurry vision and nausea makes migraine headache a possibility, especially given no relief w/ NSAIDS. So, see a headache specialist for diagnosis and treatment. Good luck!

It is not feasible to provide a meaningful opinion without additional history, physical examination and may be some tests. It would be prudent to see a doctor. Start with a primary care provider and may need to consult with a specialist. Wish you good health!