I agree with @TwoCrows. I have IC in my flock and decided to treat. They are my family and I help them as much as I can. Culling is not an option for us.Hello and welcome to BYC!
I am so sorry you are dealing with these issues. Mycoplasmas are difficult to treat and leave the birds carriers for life. My flock was diagnosed with MS (Mycoplasma Synovea) at 8 months. I was just getting started with chickens and inspite of people suggesting I cull the entire flock, I chose to keep and treat them. It took nearly 3 months of antibiotic treatment to beat down the bacteria. It was expensive and traumatic on all involved. I didn't lose a single bird however during the course of cleaning them up. The problem with Mycoplasmas is they know how to hide in healthy cells going undetected by the immune system, which does leave the birds carriers for life, on the weaker side leaving more suseptable to odd issues during their lifetime. Some problems I was able to treat, others not so much. I moved the flock to a new coop, new grounds, I did add birds over the years, lost a few here and there however the disease never reared its ugly head as it first did originally. I don't regret keeping my original flock and many did live into their teens, some were lost at a few years in. This is a decision only you can make as to whether or not you keep them all or start over, I know its a tough position to be in.