Abdominal pain. Cause behind this pain.

I got married recently & 26yrs old. Very recently (1week before) , I have severe left side abdominal pain. It often comes and goes. Since 3days, I am experiencing lower abdominal pain, similar to periods pain. Sometimes along with this left side back pain also accompany. I had experienced this mind of pains 1month back also. But easily went off. First I thought I am pregnant and these are cramps. But so far no other symptoms have come. My period due date is after 1 and a half weeks. Usually I have painful periods (only on first day). I also had kidney stones when I was young. (18yrs). Took tablets and it went off. Later I was again diagnosed with small kidney stones but Doctor said it wil go off. -Drink plenty of water. After that I Haven't scanned. And everything was normal. Now I have no idea what is the reason behind this. Though it comes only often I am afraid if this is something serious. Please let me.know what is the cause behind this pain.