Tiel, with cyst, advice please!!?

I'm so sorry to hear that your tiel is not well. I don't have any tiel's but I have 'keets and they love spray millets, maybe you should try that and some cuttle bone. Since your tiel has come this far, is go with the surgery because if you put him to sleep, you will always wonder whether or not you've done the right thing, and he may seem weak, but you never know, he might just get through the surgery, if not, at least he was given a chance. I will pray for your lil 'tiel. Hope all goes well