What Causes Severe Lower Back And Lower Abdominal Pain?

I am having severe lower back pain, and lower abdominal pain when I use the bathroom. I don t know if they are related. Because I have ehlers danlos syndrome and possibly have endometriosis. I don t know if the back pain is being caused by my EDS. And if the pain in my abdomen when i urinate or go number 2 is being caused by endometriosis. I guess my concern is if i have a UTI and I don t want to go on not treating if it is. I ve taken Ibeprofen 800 mg and Tylenol and neither have helped. I also have taken a bath of Epsom salt with no relief. A heating pad does help relieve some pain in my abdomen. But no relief in my low back.