Stillwaiting, hi & welcome. I'm sorry for your problems & frustration. I had some similar symptoms. I'm only a dumb patient, so please read in that light. CROHN'S & IBS (etc.)
. I had 20+ years of episodic problems, starting in mid-20's, with bouts lasting as long as 8-10 weeks. (Show-stoppers, I agree, awful.) What my drs. did differently: I had the invasive tests (upper/lower GI series, endoscopies, and colonoscopies) multiple times, not just CT scans. In your shoes, I'd ask if I'd had all the appropriate tests. That also might include bloodwork: preliminary Celiac tests might be blood tests?
Also, you could ask others which tests they had. Possible boards to try: Celiac, Crohn's/Ulcerative Colitis, and IBS. To get to those, select "Find a Board" hyperlink (blue bar above), then select the hyperlink that sorts the results into alpha order.
Also, if you've taken any GI meds or tried dietary changes, did any help? I took Librax for years, used Metamucil, limited my diet. Nothing helped, which should have told my doctors and me something. (I yammered, to no avail.) SKIN RASHES
(face, arms, stomach, legs). Those could be another path to diagnosis, or at least to narrow down possibilities. Have you seen a dermatologist? Dermies can biopsy, and perform immunofluorescent stain tests on the sample. So can dermatopathologists, super-specialists who are both dermatologists AND pathologists & can do their own labwork. (Those are more often found at teaching hospitals.)
I this certain rashes are possible in certain GI conditions, like Crohn's, UC, and Celiac. If your rashes turned out to be one of those, that probably wouldn't "prove" you have one of those conditions, but it could add weight. And an array of rashes are possible in lupus. While only two "make" the lupus diagnostic criteria list, there are anywhere from 12-15 lupus-specific rashes. (Additionally, people with lupus often get certain non-lupus rashes.) You could describe your rashes in more detail on any/all of those boards, to see if it rings any bells with other skin patients.
Regarding ANA in lupus, it actually is possible to have systemic lupus with a negative ANA; but this is rare, only 3-5% of all patients. This "subset" is called Ro-lupus; it it, ANA remains negative but anti-Ro is positive. The two rashes most likely in this subset are Subacute Cutaneous Lupus Erythematosus, either annular (in mature form, looks like targetlike rings) or papulosuamous (psoriasiform, which looks like psoriasis but isn't). These two rashes are abbreviated SCLE, they mostly don't scar or depigment or itch, and they tend to be VERY photosensitive. ANA
. I don't think total credence should be given to a single ANA test! That's because ANA can vary as flares come & go, so timing can be critical. And the tests are notoriously hard to perform; not all labs are good at them. And as I said above, there are instances of ANA-negative conditions---lupus for sure---but I can't speak to the other AI's (sorry).
I was finally Dx'ed with that "Ro-lupus", which is admittedly rare. It took so long, partly because my suburban "ologists" were limited in their knowledge & the too-limited tests they ran. But some of was my fault too, for not ramping up to better doctors sooner. (Did I not admit that I was a dumb patient?
I hope others chip in. There are recent posts just on this board from people with GI issues plus rashes, so I know you're not alone, on this board or on other boards.
I hope you drop another post when you read this. I'll say bye for now, with my best wishes, sincerely, Vee
P.S. Hang in there!