I have had 18 abdominal operations including insertion of J-tube, repairing a bowel perforation, and issues with MRSA. I had mesh put in that I was allergic to which led to about 7 abdominal operations. I have had MRSA 4 times in my gut. I had an abdominal wall constructed due to infection. I have titanium tacks in every rib, and screws in my hips and pubic bone holding this reconstruction together. Despite the last surgery being 4 yrs ago,at times the pain feels like it was yesterday. It is a combo of chronic and acute pain.
Standing, rotating, bending, etc, all make the pain worse. I was able to get some pain control with the help of my surgeons, the ones that did the abdominal work, writing to a pain specialist recommending pain care. This all but eliminated the "its all in your head" syndrome. I have found that finding a pain doc who will treat with just medication has been a battle. I cant get injections due to the MRSA. I go to therapy, group therapy, meditate, etc... It seems like pain control that isnt standard it hard to get.
Hang in there and speak to your surgeon.
You should see a neurologist, you should have a CAT scan or MRI, whichever one he wants to order, and be evaluated for a nerve problem in your abdomen. I first thought it might be in your spine, as that can cause your symptoms, but you did not mention your back hurting at all. So, that's why I think a nerve group in your guts may be compromised for some reason, possibly scar tissue or an accident during surgery, which your neurologist should be able to find, and he may be able to either surgically fix it, or he can at least give you some good medications that will make it easier to live with.
I am so sorry to hear about all this shocking stuff that has happened to you, and now you are in so much pain that your whole life has become quite unhappy, I'm sure. I have similar problems as you from a car accident that tore up my spine, I also can't stand or sit very long, the pain can get unbearable to where it's hard to even get out of bed, so until I can afford to have a scan and surgery, I take pregabapentin and that combined with clonazepam significantly lessens the nerve pain, and thus at least my mood is not so scary, but I remain restrained in what I can do even around the house, and I am permanently disabled and on social security on account of it all. At least, tho, you are much younger than me, and with either a resolution of the nerve problem with surgery and/or minimizing its effects with strong medications, you will be able to push through all this and hopefully begin to resume at least a few things that you enjoy.