My shih tzu had a lump on her face and we found out (after 18 months), it was her salivary gland. It was pushing out her eye. With her heart murmer and her age of 14, we could not have surgery done. We just lost her to kidney disease.
It will cost over $1000 for him to find out. MRI and everything else. The vets see dollar signs over this issue.
Good luck