Severe migraine that is still ongoing. day 4. blurry vision. sensitivity to light. numbness. mri, mra and ct all negative. infection ruled out. should i ask for further testing or is this reassuring ?

Time to start trying treatments I would think. There are many and only well to see which one works best in you is to try them

Potentially, you have developed "Status Migrainosis", and you will need to have your doctor provide appropriate medication to break up this pattern ASAP. "Further testing" would likely be fruitless, and instead would ask your physician to provide therapy. An experienced neurologist may be helpful.