I would think it was a seasoning on the steak way before I'd think of something parasitic. If it was parasitic, symptoms wouldn't appear so quickly, and the symptoms would be intestinal, not a migraine.
It could also be wine, beer or another alcoholic beverage, if you had that, too. Cheese is also a possibility. Parasitic worms wouldn't even make my list of migraine triggers.
Hello~Certain food sensitivities can occur later after eating something you are allergic/sensitive to, so, it is possible. If you still aren't feeling well or symptoms get worse, then it would be a good idea to see your GP or at least call and let him/her know what is going on.
Hello. I had migraines related to food years ago. It was from food flavor substitutes. Once I cleared that out of my diet, no more migraines. So, you are worried about worms. I've read about this. The thing to note is that when those types of symptoms appear, it is a good deal of time after ingesting the worm/larvae laden food. It's not like the next day you'd have neurological symptoms. I would see if anything else happens. If not, write it off as a fluke. My guess is that will be the case. Have you eaten buffalo before?