Endometiosis cause pelvic pain, pain with hard stools, change in stools, constant period-like cramps?

Yes. Endometriosis involving the recto-vaginal area certainly can cause those symptoms. A careful examination by your gyn should be able to determine if this problem is present. Fortunately minimally invasive surgery can cure the problem in most cases. Make sure your gyn is an expert in laparoscopic procedures of this type so you can avoid a large abdominal incision.