So sorry that you are dealing with this too Kitty.
The HUG and a few other not so nice Sx have kept me from sitting for very long over the last 3 weeks. Thus have only been checking in briefly here from time to time. Hurts too much during and after
I get some temporary relief from the HUG pain and inability to take a full breath by pressing (or having someone else press) on the abdominal muscles just under the rib cage. Just push on one area, hold for around 30 seconds, then move to another area; or the muscles will get sore, especially if they are in spasm.
It helps more if you can push the abdomen outward and try to breathe deeply while pressure is being applied. Hurts like heck...sometimes even refers sharply into the back; but after just a few minutes and some breaths like this, you will most likely be able to catch your breath and the pain will abate for a little while.
This also seems to help with digestion and bowel function.
The HUG pain, spasms and breathing problems come back for me if I stay in any position for very long (especially sitting), and after eating.
Good luck. Hope that you feel better soon
With love, Erika