Cramps between periods

I am writing this to gain some info if any of you have expirienced what I am. For a couple cycles now, I would say since about December, I have been getting cramps AFTER my period ends. Anywhere from 3-5 days after. I then have them up until my next period. My period is always on time and lasts about 6 days. I did however have a miscarriage in January and experienced this before that just not long enough to see a pattern until now. AF came on time this past month and I took 6 pregnancy tests before AF came, during and now today just to be sure. All negative. Hoping someone can give me some insight on this topic.