Though only 10-15% of patients experience the discomfort you describe, it is real and it is uncomfortable. Tylenol is usually effective in combating the discomfort. Of the few patients of ours who have described the "late onset pain" that you are experiencing, we have found that prescribed Neurontin is very effective in alleviating discomfort caused by the nerves rebounding from the CoolSculpting procedure.
Our practitioner has performed close to 1000 treatments and has discovered that of those patients who experience this pain, it is from treatments with the very effective and great surface area large treatment applicator. It is possible the small applicators could produce the discomfort, but in our experience we educate our patients on the possibility of late onset pain especially with the large applicator.
Rest assured that those nerves are not damaged, they are just angry and they will return to normal. It is a very temporary experience. Contact your CoolSculpting provider for options.
For comfort, some patients prefer looser fitting clothes and some prefer more snug compression clothing (like exercise pants or Spanx). See what helps you to feel most comfortable. Either icing the area or warm therapy can be beneficial (protecting the skin with a towel as barrier) - again - one or the other with likely feel more preferable to you.
A trained and experienced CoolSculpting practitioner would not place the applicator directly over the navel, but even treatments around the navel can make it feel hypersensitive because it is involved in the treatment area. If you have any concern about the area or possible hernia, do contact your provider for evaluation and peace of mind.
A few more weeks and you should start seeing some change, but remember, the elimination of fat cells naturally is a gradual process, so the most dramatic results are a few months down the road. Good luck to you and thank you for asking this question. I hope the information is helpful to you.