Yes, it can take years for some for the rash to subside.
Yes, the ENT is right -- it does look herpetic. That's WHY they call it dermatitis HERPETIFORMIS Mr. ENT!!! It presents in a herpetic manner. That does not mean it's herpes!!!!!
Yes, the rash can present any old where on the body so if it presents on the nose then it presents on the nose.
You already know that in order to test for it you have to do a gluten challenge. I don't blame you for not doing that. i wouldn't either.
I CAN think of a reason it cleared up while you were taking doxycycline. Follow me here ~~~
The medication of choice for dh is Dapsone which is an antibiotic but it can cause big, bad, liver problems & one has to be monitored closely with blood tests while on Dapsone. Dapsone is a sulfa drug. After Dapsone are a number of antibiotics, mostly also sulfa drugs but here are some that are used. Sulfapyridine, sulfamethoxypyridazine, colchicine, cyclosporine, lymecycline, nicotiniamide, and TETRACYCLINE. All of those are considered to be less effective than Dapsone but then we are all individuals aren't we and what works for one may not work so well for another. At any rate you were taking an antibiotic in the terramycin class.
Now, I believe you when you say you are rabid about not getting cc'd. BUT we want to make sure something hasn't slipped under the radar here so don't get upset okay? We just want to check some things & make sure those aren't exposing you to gluten b/c it is entirely possible that this is coming from a low level gluten exposure & it's keeping the rash firing on you. Here goes:
Kissing any gluten eaters when they have not thoroughly brushed their teeth first?
Exposure from kids gluteny hands or cheeks?
Pets -- pet food that contains gluten -- you can breathe it & gluten dust goes down your throat or kissing your pets with gluteny mouths or after they have licked themselves & gotten gluteny fur.
Vitamins, meds, OTC meds and things like probiotics.... do you make sure none of those contain gluten?
Last but not least. Do you eat oats? Certified gluten free oats? If you answered no to the items I listed above but yes to oats it is possible you are 1 of the 8% of celiacs who actually have a reaction to even certified gluten free oats. I am. That one took me a long time to figure out!