What Causes Headache While On Zyprexa?

I stopped zyprexa 30 mg daily/7 years rather quickly, last week of dec/first week of Jan this year. Sinus infection/pain/issues and allergies, which (coincidentally, I thought) were absent for years, began about Jan 13. Terrible sinus pain and other things (panic, insomnia, later itching) I ve now learned are symptoms of zyprexa withdrawal. Now know zyprexa has strong antihistamine effect And is sometimes used for prevention of migraines. Was diagnosed with Migraines in March and began mag, b-2 and topomax. By then my headaches weren t as severe. Abortive I first tried in early March didn t work- I think now they were chronic. lasting days, and I just couldn t take it early enough in the cycle to stop them. Found home remedy which almost always works- Cayenne/honey/water, used it while waiting for preventives to start working. Then late april or early may was diagnosed with dermatographism- for me mainly intense itching and a few hives- and for 7 weeks allergist had me take 2 xyzal AM and 2 Zyrtec pm plus pepcid femantodine as needed. Now I know itching may have been zyprexa withdrawal symptoms. After a few days on the antihistimines, noticed migraines completely stopped- at that time I assumed preventives were working. As skin condition cleared up, I greatly reduced antihistimes. A few days later migraines reappeared. Mostly mild but interfered with daily activity. For first 3 days I took rizotriptan as prescribed by neurologist, which worked (one of those days I had to take a 2nd one) then thinking I was taking too many, returned to cayenne and saved rizo as last resort. This was largely successful- have taken 1-2 rizo/week since, and they work when I take them. Now on day 11 of prednisone prescribed by neuro (20mg 5 days, 10mg 5 days, 5 mg 5 days). Kept having migraines next 7 days, also very congested. No pain Day 8, I thought it was over! Day 9 was pretty bad- tried cayenne twice, had to take 2 rizo, it did work. Friday day 10 was able to abort before actual pain developed by taking cayenne. But still had severe congestion, runny nose, dizziness (new for me)and fullness in ear on migraine side and just didn t feel good. Called both allergist and neurologist- haven t connected with neurologist yet, allergist s office said migraine/congestionl/ear symptoms not being relieved by prednisone means the current headaches aren t allergy-triggered (I d thought the January ones were triggered by a new allergy, and as shots have helped reduce sinus infections in the past, planned for allergy testing). Yesterday and today eliminated some potential food triggers from breakfast- They always start After I ve been up a while. No migraine pain or congestion or allergy symptoms today, Feel Good! Question: if prednisone didn t work for current migraines, does that suggest antihistimines won t work as preventive? Do you think the prednisone is working- just took a long time? Is it possible I m still having zyprexa withdrawal symptoms? (Am also faxing this info and these questions to neuro tomorrow) Thanks, Connie