Need more history, things like past medical problems, medications, drug use, etc. Differential as I see it includes infectious, autoimmune, vasculitis, drug use, medication, environmental (especially considering the burn pit). It's very odd that it would take years after that exposure that these ulcers would start, but not impossible. Why has he lost countless jobs? What did previous skin biopsies show? What have his labs shown?
My husband is fighting for his disability because this is so debilitating he cant work. But without a diagnosis the disability people keep denying himHire a VA disability appeals attorney. It cost me 2 grand twice, the first time got me from 30% to 90% and the second time got me from 90% to 100% total and permanent. I personally have far less severe injuries than what your husband has and was suffering the same issue.There are also attorneys for SSI/SSDI benefits, though I havent personally used them as applying for SSDI as a 51 year old is relatively easy. As a 27 year old though it is damn hard and you likely will need a lawyer or a few years of trying, and a lawyer works out cheaper in the long term.