Pain In Side More Condition_symptoms What Can Cause You To Have Abdominal Pain On Both Sides But More On One Side?

What can cause you to have abdominal pain on both sides but more on one side? - pain in side more condition_symptoms

Abdominal pain is not so bad come and go during the day. I started my period a week late. I symbolic, but the pregnancy tests were negative. I feel sick to the stomach when I eat. My breasts are tender. I missed a couple of times. I have no fever. Oh, and sometimes my lower back starts to hurt.
Suggestions?
Thanks