What Causes Memory Lapses, Syncope, Nausea And Headaches?

Hi, I'm having weird symptoms and I can't figure out why, I've been having sudden insances where I don't remember what happened five minutes earlier, I've almost fallen on the ground a few times, I feel nauseous at times, and my head feels really weird, like I can't think straight and I have a slight headache. I took excedrin migraine this morning and I think I took 1500 mg on accident I don't really remember since I was in a hurry for work, would this all be because of the excedrin?