Not sure I can give you any definitive answers because the reason for your tree's die back is not able to be determined without seeing the tree in person and perhaps running some tests on it to see if there is any infection that is involved. Even then diagnosis may be a hit or miss proposition There are some trees that can actually fruit themselves to death. It is rare, but it does happen. This is especially true with trees that have not had sufficient sizing and then are allowed to carry a very heavy crop. That is, a crop much larger than the size of the tree can support. At this point, you definitiely need to remove the blooms to see if the tree will respond with pushing new vegetative growth. I would not assume the tree is doomed, but if it does come back, you need to keep the amount of fruit it carries limited until it gets considerably larger than it was when it had its last heavy crop. Good luck...I hope this helps.

Harry

I would get the soil tested to make sure there aren't any macro/micro nutrient deficiencies if you haven't done so already.

Another possibility is fungus.

This probably doesn't apply to you but your situation sounds like the problem I had in my last house. I lived on a small island and ALL my fruit trees dies within three years because the roots went down to the salt water below the house.

For that reason I never planted anything I didn't want to lose in a few years.