Hi!
It could be endometriosis, it certainly has characteristics that suggest endometriosis, such as worsening around the time of your cycle. The way to find out is by
laparoscopyDiagnostic laparoscopy
Gynecologic laparoscopy
Incision for abdominal laparoscopy
Laparoscopy
Pelvic laparoscopy.
I usually have my patients follow a good bowel regimen ( fibre/water/milk of magnesia) for a few weeks before surgery to rule out irritable bowel syndrome. (the part of your story that is suspicious for IBS is that the pain moves around.) If the bowel regimen helps, then GREAT! If not, then we move on to laparoscopy.
Another option is to try oral contraceptive and anti-inflammatories ( Aleve, etc) for awhile. If these help, then surgery can be deferred, and a presumptive diagnosis of endometriosis can be made.
I hope this helps!
Good luck!
Dr B