What is this growth on my dogs eye?

Tara

I noticed a stye like growth on my 6yo pit bulls eye. The vet didn’t seem concerned and gave me a cream to put on it. A few weeks go by and it’s only getting bigger. Called the vet and ordered a different medication to try. Nothing is working. I’m afraid it’s something more serious that the vet isn’t picking up. I’m concerned bc it’s only getting bigger. My dog doesn’t seem bothered by it at all btw. Any ideas on what this might be?! Thanks!