Interesting donation.

I've donated quite a few times. I'm at grifols now. Today, however, unlike most days when I donate about 97% in, I got into a cold sweat and tingling sensation in my arm spread to chest. Everything seemed to get brighter in my vision, and there was like a dark cloud floating across everything. I assume that I wasn't too far from passing out when the saline kicked in and everything went back to normal. I figure I wasn't hydrated enough. I had eaten before I went. I'm at home now with water with liquid I. v. Your thoughts ?