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Hi, I can help you with your question today.
I'm concerned that what she has is more serious than just halitosis, especially since you already detected an ulceration or other lesion on her tongue.
This could be an indication of a chemical burn, thermal/electrical burn, viral infection, or oral cancer.
I highly recommend having her evaluated by your local vet. I would start with a physical and careful oral exam. If she is too painful to allow that, she may require sedation.
Based on the exam, we may already have a diagnosis. Then we can start a targeted treatment plan.
Some general things that will likely be prescribed are an antibiotic (such as Clavamox or clindamycin) and pain medication like buprenorphine.
If we find an ulcer, a prescription for sucralfate can also be helpful. Your vet could also give you a prescription for "magic mouthwash" to fill at the human pharmacy. This can help with pain from ulcerations.
Please let me know if you have further questions. I am happy to continue until I provide the service that you seek.