Weird period

So, here's what's going on with me:
6 DPO, started cramping. Got really moody. Cramping and moodiness stopped yesterday (11 DPO). Normally my periods are very painful and very heavy. Yesterday morning tested negative with an FRER. Thought I started my period. Had a lot of pain and a little blood. Just a tiny spot. So I put in a tampon and went about my day. I was an hour from home and the entire way home, cramping really badly TMI WARNING when I got home I had diarrhea, which is normal for me on my period. But after that, the cramping was gone completely. There was only a spot on my tampon. It was heavier than spotting, and bright red. This morning there was a very light amount of blood. More than spotting but lighter than my normal period. Bright red. Normally my cramps are so bad the second day that I can't leave bed and I'm throwing up. Now there is absolutely no pain. Has this happened to anyone else? Or do you have any idea what it might be? My temperature is still above cover line