Health - Headaches After DXM Use?

[RoboCop]

Swim sent me this paragraph about his DXM use I thought I'd post his question here:

Alright me and my friend have been doing robo for a while now we started doing 4oz bottles and quickly went to 8oz bottles. I would trip on an average of 1-3 nights a week all with a diffrent 8 oz bottle and he did it just as much as me. Anyways after about a month later none of us really had any problems doing it until recently. I was tripping at my house. I got a headache, but it was pretty abnormal it was concentrated above my right eye beyond my skull where my eyebrow is just in that little area. It wasnt a very bad pain but it was uncomfortable and i had it on and off for a few days. I thought nothing of it until i talked to my friend who said he is gonna lay off it for a while when i asked him why he said he was getting a terrible pain above his eye. Which i thought was wierd as hell. Anyone have any ideas on this?