Passing out/blacking out

Tramadal (I think that's how it's spelled?) for the pain and it was helping. I haven't been eating as regularly too. Every other month I get my period on the 13th and it's usually pretty painful so this wasn't too out of the norm. This morning (the 14th) I got up to use the bathroom and change my tampon. After I changed my tampon I bent down to throw the plastic part away and when I stood up I became very light headed. I thought I stood up too fast so I sat down but it started to get worse. Before I got too bad off I went to try and get my mom up. As I open the door I started to fall to the side and hit my chin off a heater in the bathroom (I now have a lovely bruise on my chin) everything went very dark and I only laid there about a minute. I was then able to get up and go to my mom and we believe I passed or blacked out because I may have stood up to fast and I haven't been eating as good. But I want so other options because it was very random and scary.