It sounds as though cramping is common for you during menses but this month you are having cramping and your menses has not started. It is a good idea to check a pregnancy test as you have done. Even though you have had a tubal ligation there is a small chance of pregnancy and in fact it increases your risk for a tubal pregnancy also known as ectopic pregnancy. Particularly if your cramping is worse on one side than the other.
The other sources for the cramping could be infection in the bladder or pelvis. Sometimes this is the only sign a woman may have with a bladder infection, even though more commonly you will have increased urination and burning with urination I have had patients present with just lower abdominal cramping.
We would have to consider abdominal causes for the cramping as well including infection in the abdomen such as diverticulis which is more common in people older than 50 but still something to be checked for.
Sometimes constipation can cause lower abdominal cramping but it sounds as if you are having regular bowel movements.
Kidney stones can cause a cramping in your lower abdomen usually only on one side however and the cramping would be intermittent.
At this point given it's been 5 days you should seek medical attention.
Sincerely, Jennifer. I hope my answer helped you. If it did please be sure to give me a good rating. If it did not please contact me as I would be happy to help you further.
