Great question...
I get headaches just like that... I even get fuzzy/numb skin feeling in my face/neck and my eye will twitch and droop. It effects my whole left side which is where my RSD is located. Last week though, it happened on my right side (weird). Doc said he thinks it is just a reaction to stress. I take migrane meds (Imitrex) when I feel it coming on but the last two times it didn't even touch it. I put ice packs on my head and eyes and stay in dark cold room and it seems to ease it up some. Any ideas out there?