Bottom Lip Sore won’t heal

Hello ny husband has had a bottom lip sore for sux months. Went to dermatologist and prescribed chemo cream. This peal his whole bottom lip off severe pain level 11. He went to an ENT doctor and he did a biopsy (no cancer) but now his lip is half gone and in even more pain level 12. He has been prescribed 10 different creams, 2 rounds of antibiotics, now going on 9 months and worse off because of 2 injections on Prednisone that sent his blood sugar through the roof, 2 more injections if numbing fir the biopsy- injections pain level 15 - I feel so bad for him and no one can help. He is diabetic, high blood pressure HELP !! Can we make an appointment at the MAYO clinic?