dwarf japanese cherry blossom problem

i have one of these in a large pot in the garden in full sun. It had previously been in the ground for 2 years until we put down a patio, at which point we transplanted it to the pot. We have kept it well watered but the leaves began going brown and curling about 5 or 6 weeks ago and now the whole bush is almost brown. We have never pruned it and it is now about 3 feet high and wide. anyone got any suggestions?

 

Hi Currie
The only thing i can think of is stress, keep an eye on it but dont overwater give it a feed ,then put it in a sheltered spot over winter and see what next spring brings,

 

Hey - thanks. It is a lot better this year. Thanks for the advice!