HELP Sick boa!

[Marinella]

I have a 17 years old boa (I have her from the age of 9 months). I live in the countryside and I don't have any vets specialized in reptiles around. She has a respiratory infection for two weeks now (although I suspect it was longer-just not noticeable). She hasn't eaten for over a month, she is active and seems healthy except for her mouth (one side is swollen and makes noises when breathing). I started to treat her with Baytril (which did the job 10 years ago). However, since I didn't see any amelioration, I went to see my vet for advice. He has some knowledge (and who got in contact with a specialist) so he told me to continue with the Baytril and to clean the necrotic tissues around her mouth and to desinfect. He also observed that she got like a tine hole (an ulcer) in her mouth. He also gave me Vit.C to administer every two days. She refuses to eat so he wants to force feed her. The expert is 250 km away and at the moment I can't make such a trip. I would appreciate any suggestions.