Lower abdomen and back pain. Evident!

Lower abdomen pain and back pain which I thought was menstrual cycle cramps I have had problems during my menstrual cycle since I was 17yrs. I didn't have much pain, but I used to faint sometimes. Consulted gynaecologist and got prescribed some medicines which I took for 2-3 yrs until I started getting allergies like my swelling because of that. I consulted one more gynac 2-3 years back when the pain started worsening and did scanning which came out to be normal. It's lower abdomen pain and back pain. Continuous leg pain, mostly starts from thigh. And if I'm sitting and try to even cough little hardly, ik that im gonna faint. I get the leg pain of the side same as the lower abdomen pain. And thought it was something to do with menstrual cycle but the other scan was also normal and ruled out endometriosis. Sometimes have that memory gap and start sweating slightly and from past week I have been having light fever at night and sweating and also the pain is getting more evident