That really sucks.

I've heard that side stiches are from lack of blood flow to the diafram area. If that's correct, I would try Hot/Cold therapy. Apply a bag of ice to it for 5 minutes then a heating pad until it's warmed up and repeat 2-3 times per session. I'd do that at least once a day for a couple of weeks. This would do on a macro level what the Ultrasound does on a more micro level.

Good luck

How do you get relief when it comes on? Where exactly is the pain, costal cartliage, Upper quadrant, lower quadrant, centralised or lateral. Give me an anatomical landmark. Have someone push firmly onto the tender area (deep), does this reproduce the pain? If so, do a half sit up and redo. Does this now abolish the tenderness or make it worse??

Be careful with heel lifts. If you are going to use one it must be because of a structural leg length problem, not just because on laying prone there is a variance. For instance, an external tibial rotation will shorten leg length, a rotated inominate or sacrum will also do the same. Ensure all of this is checked by someone with an expertise in the area (such as a chiro/osteo) before you muck with it. A heel lift in someone who doesn't actually need one can create magnet reflex issues and alter left/right brain function. Can be neurologically damaging.