Cramping?

xdoublerainbow

I went for a run today and I was pushing myself a lot harder than I usually do because I was trying to beat a personal time, which I did. I'm now running 2km in 10.45seconds. After I finished my run I noticed that I started getting cramps like I was getting my period (sorry if it's TMI) but it was way lighter than they usually are and it only lasted for about five minutes. I am definitely not supposed to get it yet so does anyone know why this could be happening?