Please Help My Cat

This is Buntis, my 8-year old female adopted cat. She has been in pain since September 2019 due to her swollen gums. She drools a lot. She's not able to clean herself as much as before, hence she's always grimy. She got thin 'cause she can't eat sometimes. Poor cat!

We've been to four different vets, but there's no improvement, and also because I don't have enough money to cover all expenses such as consultations, tests and services, medications, surgery to extract her teeth which is very expensive etc. I also plan to get her spayed when she's better so she'll be healthier. Please help my cat to be well again. She's a very good cat, gentle, beautiful, and old. Any amount will do. Thank you and God bless.