Question on Veterinarian

I have a dog named Maddox that was seen for a corneal ulcer ( that’s what they said it was). They did the staining of the eye, gave him antibiotics and the cone of shame. Sent him home. Came back two weeks later and said seems to be getting better. This went on for 10 weeks. Checking it every 2 weeks, multiple stains and I kept questioning that it doesn’t look like it’s healing. Chose to go to get another opinion and they said it won’t get better as there is an object in his cornea and needs surgery. Did the original vet misdiagnose or am I mistaken. Shouldn’t they have noticed this in the beginning? All this money wasted and now how the hell do you pay for this surgery after wasting all the money of 6 different vet visits.