2 periods in one month

So I have normal cycles, they last up to 4-5 days. My first two being heavy and the last few days it gets medium to light or just stops completely. I might skip a month due to stress but the next month it comes back and it’s completely normal. I missed December and started my period at the beginning of January. Yesterday (exactly a week after my period ended) I started cramping which I just thought it was a stomach ache and later today at work I felt a gush, I thought it was discharge but something told me to go check. Blood but black; almost soaked through my jeans. Got home from work hours later, used the bathroom and it was slightly red. 2-3 hours later before bed I had to use the bathroom again to see blood, all red not black. Has this ever happened to anyone?