to cut out red meat?

Well, being vegan I encourage any reduction in meat consumption. However, have you tried keeping a food journal for a few weeks? It could help you more accurately identify a common food that may be triggering headaches. Of course, you could just cut out the red meat and see what happens, but if that doesn't work, a food journal could be helpful. Cutting out red meat isn't going to have adverse health effects. Just make sure you are eating a healthy, varied, well-balanced diet.

You might also keep an eye on whether wheat/gluten containing foods are triggering your headaches. I used to get headaches pretty much daily (amongst other problems) but only recently found out that I'm gluten intolerant. I haven't had a single headache since ditching the gluten from my diet. It never occurred to me that it was even a problem.

Could try using organic grass-fed beef too, would be a better quality at least.

I'm on the other side. Don't get me wrong; if red meat really is causing you problems, cut it out. I cut out carbs and have eliminated mood swings, cholesterol problems, hormones, etc.

You might also keep an eye on whether wheat/gluten containing foods are triggering your headaches. I used to get headaches pretty much daily (amongst other problems) but only recently found out that I'm gluten intolerant. I haven't had a single headache since ditching the gluten from my diet. It never occurred to me that it was even a problem.

i am sure it is red meat because i would only get a headache after eating it almost immediately, definately within the hour. could it be something else?

Well, it could be the red meat or something else. It can be tricky to isolate a trigger like that. Try eating just the red meat some day when you can "afford" a headache. (Fun... not.) Do the same thing with anything else you suspect. If you have a hamburger or a roll with a piece of meat, it's hard to tell whether the problem is the meat or the wheat ;-)

My big clue came when I had a bowl of cereal and noticed the headache hit within an hour. I had other symptoms too, and mentioned them to my doctor. She told me to cut the gluten and dang if that didn't solve it for me. In your case it sure could be the red meat, I'm just saying to keep an eye out in case there's more to it.

I do a really low fat diet, and after I stopped cooking with red meat at all, I shortly followed that by not eating it entirely. It really helped me lose weight, because burgers are a big temptation for me.
After my husband failed to mention the no-red-meat thing to his mother in law before we visited, I ended up adding it back into my diet, which was rough on my system. I went through a lot of pepto because my stomach would get so upset, but I couldn't bring myself to refuse the food that the dear lady had been premaking and freezing for weeks. However, digressing a bit.
It is super easy (except when it comes to in-laws) to cut red meat out of your diet. I use lean ground turkey for tacos and meatballs and no one even noticing the difference, just much less grease. I found a great brand of veggie burgers, and experiment with chicken a lot.
If there is even the slightest chance you are having a negative reaction when you eat it, then just do away with red meat. But keep a bottle of pepto around for the occasional steak.