I had Coolsculpting on my abdomen 5 days ago. I have a sharp intermittent pain behind my belly button.

It is typical to have some pain for about a week after the CoolSculpting treatment, though it is more of a soreness than sharp pain. I recommend visiting your treating doctor to determine what is going on. 

It is possible to have some soreness or pain after CoolSculpting to the abdomen.  In most cases, this is more of a soreness that may feel as if you had done too many sit-ups.  Normally, this soreness resolves by a week.  In rare cases, there may be some sharp pins and needles pain to the area.  This is a type of neuropathic pain that can be improved with a specific medication that your treating physician could prescribe.  

Coolsculpting is and excellent way of reducing fat in a given area.  Some patients experience soreness, tingling, or discomfort for a few days after the procedure.  If you are having sharp pain I suggest you return to your treating physician to get examined and determine its cause.