ID Leaf Palaver... Please!

Everything was going fine & then suddenly my poor Big Burlat Cherry Tree is developing problems! I am devastated! I have lovingly nurtured this tree - it even has it's own coat for winter!

It's in a large pot in the garden & I got it last October. It was approximately 3 foot when planted out in the pot. It did not flower this year, therefor no cherries! This I'm not worried about... I am patient! The leaves are very worrying though. It also needs pruning, which seems pretty pointless if it's dying!

Can anyone help identify what the problem is & what I can do, if anything....

Thanks in advance...

 

Looks too small to be mature enough to bear cherries, leaf problems appear to be leaf spot and (last pic) leaf miner.

 

I dont think any of the leaf problems are life threatening.

What exactly do you mean, by, it needs pruning, you have only had it since last Oct?