Sorry to hear of your chronic migraine. There is growing evidence that migraines are like a type of allergic disease. A study on chronic migraines in children showed that 93% of patients could stop their frequent severe migraines on an elimination diet (see first reference). For the first week of the study, the patients ate only 4 foods (ex: rice, lamb, apples, and brassica). If that helped reduce their migraines, they added foods back once a week until their diet was nutritious and socially acceptable. This was done under the guidance of a dietician or physician. Similar results have been demonstrated in adult patient populations (see second reference). It may be worth a try. You may also want to reduce exposure to environmental allergies (use hypoallergenic pillows, hypoallergenic mattress cover, remove dusty rugs in the bedroom, etc.) An allergist could give you a simple prick test to find environmental allergies, although these tests don't work well for detecting food allergies (see reference 1).
I had a chronic migraine aura for about 2 years and learned that my diet was by far the best way to manage my migraines. I tried an elimination diet. I cut out 7 common allergens from my diet (Milk, Egg, Wheat, Tomato, Beef, Corn, Soy) and got much better. I now eat mainly rice, vegetables, and fish and have almost no migraines.
Egger, J., et al. "Is migraine food allergy?: a double-blind controlled trial of oligoantigenic diet treatment." The Lancet (1983): 865-869.
Mansfield, Lyndon E., et al. "Food allergy and adult migraine: double-blind and mediator confirmation of an allergic etiology." Annals of allergy (1985): 126.
Monro, Jean, Claudio Carini, and Jonathan Brostoff. "Migraine is a food-allergic disease." The Lancet (1984): 719-721.