What can cause stabbing pain by belly button. feel very deep internally and worse on bending forward. no piercings or outside infection that i can see.

See a Dr for exam: There are a variety of things that can cause belly button pain. Some are minor such as constipation or gas or pregnancy. Others are much more severe and may require immediate intervention such as appendicitis, intestinal perforation or stomach ulcers. It is important that a Dr do a hands on exam and tests to determine what is going on.