Prayers for you and Cruiser. I am so sorry you have so much to deal with right now.
You need to get some sleep, and then get those tests done to see what direction to go in next. Don't get the cart before the horse. There are so many things you could speculate about right now, and it is not helping you sleep.
As far as your contract, you will need to ask the breeder for what this covers. Is none that laid out in the contract?
How hard. Hugs for you
Will be awaiting word on his condition