Thanks for using the forum. I am happy to address your questions, and my answer will be based on the information you provided here. Please make sure you recognize that this forum is for educational purposes only, and it does not substitute for a formal office visit with your doctor.
Without the ability to examine you and obtain a history, I can not tell you what the exact cause of your symptoms is. However I will try to provide you with some useful information.
It sounds like you suffer from migraine headaches diagnosed after a normal MRI and based on the description of your headaches. It sounds like your headaches are severe and debilitating. When someone suffers from frequent and/or prolonged migraines, certain treatments can be initiated to help. The treatment should include two types of medications: preventative therapy and abortive therapy. Preventative therapy is a medication that would be taken every day regardless of whether or not a headache is prevent. This type of medication is used to prevent headaches from occurring, and there are several types including but not limited to beta blockers such as propranolol, calcium channel blockers such as verapamil, and others including topamax, depakote, elavil, etc. A lot of these medications were invented for other uses and are used not only for headache but also epilepsy and depression. They have proven very effective in preventing headaches. The second medication is abortive, meaning it is used when a headache is coming on. The medication used depends on the nature of a headache. If it is a migraine type headache, a group of medications called triptans can be used. And so on. However, with frequent use of abortive medications including triptans, tylenol, advil, and others, medication overuse headache occurs. This requires a specific treatment in which the over-used medications are slowly stopped and replaced with more long-acting medications. Tylenol with caffiene, and similar medications, can cause medication overuse headache if used too frequently. Lyrica, which is used for fibromyalgia, can be used for chronic headaches too.
However, if your most recent headache has been going on for a whole month on a daily basis, one concern would be medication rebound. This is a not uncommon cause of worsening headaches in someone with known migraine disorder. Called medication rebound or medication overuse headache: medications as simple as tylenol or advil if used too much can cause rebound headaches that are even worse then the headaches for which the medications were started for. This is very common and is most likely to occur with use of any medication for your headache more than a few times a week. It can occur with all the commonly used headache medications such as ibuprofen, triptans (such as imitrex), fioricet, and commonly with any type of narcotic such as tylenol #3, dilaudid, percocet, etc. The treatment is difficult, but basically involves weaning off the offending agent and replacing it with another that is later weaned off, combined with a more long-term solution. This should be done under strict guidance by a specialist, preferably a headache specialist, or else the headache will not improve and withdrawal side effects can occur.
Evaluation by a headache specialist (a neurologist with specialization in headache medicine) would likely be of benefit for you.
Thank you for this opportunity to answer your questions, I hope you find the information I have provided useful, good luck.
It sounds like you're going through some rough times right now...I am going to send you a link to Mayo Clinic's website, and what it has to say about Migraines with aura.
Let me know if this sounds like what you've been experiencing.
http://www.mayoclinic.com/health/migraine-aura/MM00659
If you do get a diagnosis, I would be interested in what is causing all of this.
Best of luck to you.