You did the best you could do and what any of us would have done...When you go to the vet you are intrusting them with the most precious thing you have and you think they know what they are doing, so don't beat yourself up..You did nothing wrong...I am really sorry that it isn't looking better, but have hope and be thankful for the time God gave you with him, My heart goes out to you, I have been there, but it doesn't get any easier its a hard road to travel but I am here for you and prayer for you and your baby.