could you lend a hand or opinion?

D&C 25 days ago. I ovulated last Saturday. Last night in bed I had some cramping like in the uterus and pinching feelings. This morning I had a backache and cramping like af could show any moment. I had a dizzy moment where I lost balance today. And just now I had a small spotting of brown on the Toilet paper more slimy clear with brown streaks.  I did have sex three times. My boobs don't hurt which is an af sign for me. My pelvic area feels so full! I'm so confused. Do you think this could be implantation?? Or just body out of wack? Oh and I've been under 20 hcg for at least a week or more per pg test showing negative.