quince loosing bark

This is a Chinese quince, Pseudocydonia sinensis. It is ancient, collected probably in Korea and imported from Japan a few years ago. It was always very promising. Last spring I potted it into this fabulous container by Peter Krebs. and then it almost died. I still don't know what happened. Anyway, it was sitting around all summer looking dead. At my late summer meeting we contemplated to hide it in the garage because of embarassement. And then in winter it started to come again. In spring many of the new shoots suddenly died like they would forom fire blight. And now a few days ago stripes of bark came down and the whole tip of the crown is dead. Today I took off the bark where it looked dead. The rest looks quite happy I will let it grow freely all summer and then cut back at the beginning of August. I will leave the deadwood on that quince. I have never seen a quince with deadwood before. Well, someone has to start a trend.
Maybe it actually had fire blight. Or at least a deadly fungus. Or almost deadly. I hope very much that it does not spread.
I have not used any fungicide or similar. I believe in the natural strength of happy trees.