One other thing---
You might check and see if that new growth is coming from below the big knot--below the bud union. If so, rip that off, even if it looks nice and healthy. Growth below the bud is from the rootstock and will most likely bloom a lovely red color. It's possible your grafted rose died entirely (sorry!) but the strong rootstock lives on and on.
Hopefully you have at least a few new buds from the grafted rose. I had written off a few of mine, then looked again today and yippee there is growth!
