I have a umbilical hernia.last night after laying on stomach when i awoke my hernia had moved and belly button was sunk in. what should i do?

Pressure: Pressure can cause hernia to retract. Hernia is not a problem unless it gets stuck out, swells, and is tender- especially if followed by vomiting. Otherwise size and presence of hernia is not important but you may want to have it repaired for esthetic reasons and to be sure that you never have complications.

Surgeon: Usually when an umbilical hernia becomes problematic,it's because it's stuck and can't be pushed back in. However if you have discomfort and associated tenderness,have an examination by an abdominal surgeon.

You're good: Nothing. You just reduced the protruding tissue back underneath the hernia (hole) in the muscle. It will return, especially if you do heavy work or strain/cough. if it protrudes and is hard and painful, you'll need immediate attention. The elective repair is quick, outpatient, and is done with a little sedation and local anesthesia. I recommend a surgical opinion. Good luck.