Blueberry Trees

My blueberries started to ripen , turning blue & suddenly the next day the three trees all seemed to have blueberries with a tinge of red 7 look slightly shrivelled !! Rough kind of outer skin ! Could it be a fungus ?

If yes , what best to do pls ?
Thanks

They are in ericaceous soil & I changed it last year , they were doing fine until two days ago !! Should I cut of the brances so that they can re grow ? How often do they need to be watered ? Was told rain water is best for them but no rain for weeks ! So used tap water.
Thanks