Middle East - Not knowing your location I cannot research to be more specific. There are diseases that can damage both leaves/branches and fruit. My best guess is Fire Blight. There are supposed treatments that can be sprayed but where I live most people just down the tree and burn everything to start over.
Fire Blight aka Erninia amylovora usually infects pear trees but can also damage apples, crabapples, cotoneaster, hawthorn, loquat, pyracantha, quince, raspberry and some other rosaceous plants.
https://en.wikipedia.org/wiki/...
More information here:
https://delange.org/Fruit_Tree...
Please keep in mind that I am only guessing from the information you have provided.
