It shows up on an ultrasound so most definitely if you had an endometrioma attached to your ovary it would be seen and noted as a blood filled cyst (Endometrioma)
Because you had previous surgery for the cyst and a tummy tuck, what you could be feeling is adhesions. They can cause the tugging and pulling/pain etc. If it is adhesions then it will not show up on anything. Well I cant say that for sure. If it is twisting your bowels you might be able to see that.
I had two scans, on the first they didn't show up. the second one done a year later they did. I think it can depend on the time of the month they are done and how big they are. Also the second scan was at an OB / GYN specialist radiologist and they put it on a huge screen to look at it whereas the first screen was at a general radiologist who looked at it on a tiny little screen.
As far as I know CT scans can show them. Mine showed up on a CT scan. If they didn't pay much attention to your past history than you should call and have a chat with someone that will listen.
I am not sure if you can feel then when you walk or not. Wish I could be of more help there.
Good Luck!