I had the same problem but my doctor told me that was my organs starting to move around and start preparing for you to carry your child. They stopped when I hit about 10wks! I had one random period during that time also. So I wouldn't think to much of it! :)
It's your uterus stretching to make room for baby. You're gonna have it on and off for awhile.
Around that time I had terrible cramps. Idk why but my baby is healthy and fine. Just beware of bleeding