Aww, I'm sorry Morgan. This is actually the first thread I read after making my account (I've been an invisible member for just over a year now...), and I was hopeful as I was reading through the thread. I don't want you to feel guilty please -- what happened to your guinea pig could have happened to most of us; I know I've had an accident or two in the past, as I like you was not aware of their inability to perceive depth.
I think the most important part of this thread is that it shows how even when an accident like this happens, follow up care is important. You had issues with the vet, but ratherthan giving up you kept going until you knew exactly what was wrong and what you could do.
I hope if anything happens to my guinea pigs in the future that I am as persistent as you.