Miscarriage and menstrual cycle

ken
In March I had a MC and I started getting my normal periods back in April. Now June is here and my cycle was supposed to start Tuesday and it's still not here and it's almost Thursday. 
I am having pain in my lower back on the left side like I did when I MC in March but it's not as intense. I also had mild cramping like when I usually have my period. I took three cheap pregnancy test today and they all say negative. I have never had irregular periods and idk what's going on! Any help or advice is greatly appreciated!!