I have excruciating pain in lower back and lower left buttock during my menstral cycle- I have been to Er with the pain before and they did see a kidney stone but said that wasn t problem. This has been going on for years. I ve had a hystectomy bc of endometriosis. My labs and urine are normal. Occurs monthly like clockwork, but lasts off and on in waves from 2-3days to up to 2 weeks. The pain is very sharp- takes breath away and just have to move around but nothing rids it generally bringing me to tears but not throwing up nor fever. The last time, I got to where I couldn t urinate- during the pain-- curious if the kidney stone could be the reason for this. -- and maybe cause the nerves to be affected in that area??I do seem to swell often-- or rather retain fluid very easily as well.