Mystery pain in right lower abdomen and pelvic region...help!

For the past 5 years I have extreme pain in lower right abdomen and pelvic area, it comes super strong once or twice a year and is so bad I go to the ER every time. I have had ALL the tests done, upper/lower GI, endometrial biopsy/ blood tests/ internal and external ultrasound, pap, I dont have appendicitis although I did have an appendix flare up once but it healed itself. I am very physical, running and working out daily, I eat a keto/low carb diet…Im in menopause but this started before menopause, I am not on hormones. The doctors are miffed…anyone have any thing similar? have a diagnosis? According to tests there is nothing wrong which is the absolute worst diagnosis

Could it be just trapped gas in your gut? or gut contents having too little fluid or bulk to move easily and you are feeling extreme spasms ? Do you get enough fibre in your low carb diet.?
Did this start as you started the low carb diet?