Bad Cramps 6 DPO- Should I be Concerned?

Hi everyone. I had a mmc in May and had a D&C June 3rd. I bled a lot the first week after, so much so that I went to the ER on day 5, but everything looked normal. I got my period in late June and I'm on my 2nd full cycle, and TTC again. Today is 6 DPO, and having bad cramps..basically feels like full blown period cramps and it's been for a few hours now. My cycle is usually 25 days, so my period isn't due for 7 days. Last cycle my cramps were early but only 4 days early. Of course I'm wondering if this could be implantation cramps but I have never had them before, and I've been pregnant 2 times. I don't know if it makes sense that I would get them if I didn't have them with previous pregnancies. I'm also wondering if something could be wrong and I should call my Ob. Any thoughts or advice?