That's a relatively new treatment for refractory migraine. I did find one study that suggested its use for patients who have failed other preventives.
http://www.ncbi.nlm.nih.gov/pubmed/12167140
Having a migraine for more than 72 hours is cause for concern and should be checked out. Do you have a headache specialist you can consult? This would be the right kind of doctor to evaluate your pain, provide an accurate diagnosis, and offer appropriate treatment.
https://migraine.com/blog/when-doctor-er-for-migraine/
Whenever I have a long-lasting migraine or one that keeps returning, I call my headache specialist and get his advice on how to proceed. Sometimes it's a med change or an extra consult. Sometimes the solution is the ER or an inpatient stay. Every time is a bit different. The important thing it to not let it continue. You need help to break this cycle.
Tammy