It would be very useful to have a photograph showing these brown blemishes - there are many causes of leaf browning, and its often possible to identify the cause by seeing the affected leaves.

Otherwise, how long has the tree been planted, and what part of the country are you in?

And, if it's close to the wall (and therefore near foundations), it may be struggling to maintain a constant water supply, so it can't hold on to its new growth.

Really need to see a pic as mentioned.