Lengthy menstrual cycles are most often due to irregular hormonal
levels in your system. The cause can be ovarian or in other glands. As your abnormal cycles are associated with pain, we need to rule out ovarian causes like cysts or masses etc. You also have symptoms suggestive of possible pancreatitis
or any other intestinal infection. Please get an ultrasonogram to rule out any structural lesions. You also need to have certain blood tests for pancreatic and liver
function as well as hormonal assays. Please visit a gynecologist for a pelvic and abdominal examination at the earliest.
Wishing you the best!