Amelanchier looking poorly

I wondered if anyone may know what has happened to my Amelanchier, it has not long flowered and looked fine but know is looking terrible. I do keep it watered well, (rain not tap water) and it has been fed with some standard slow release pellets every few months or so.
Hope someone way know what I should do now with it?

A picture of the foliage....


Another showing the whole tree... South is towards the window so it gets a fair amount of shade. West is towards the white chairs.
This the second year it has appeared like this...can anyone advise?. I have searched the web but have not found a conclusive answer and the local garden centres have not been able to help either.

Thanks in advance

ggg