No sign of a photo. The usual cause of flowers shriveling as they start to open is azalea petal blight, a fungal infection. This should not, however, effect the branches themselves. I am wondering about tilling the soil around this plant. Azaleas and rhododendrons are shallow rooted plants and can be severely damaged by doing this.

I also worry that you have damaged a lot of roots in tilling. No more fertilizer since they need little to none IME. Is the ground underneath mulched with shredded bark or leaves? Do you check soil moisture if there hasn’t been rain for a couple of weeks? Where are you located? Can you add a photo of the flowers and of the problem branches and leaves in the follow up comments, please.