canker or not?

Can anyone help please?  I have a problem with one of our fruit trees. I'm not sure if it's a plum or it maybe an apricot. We've only been here 1 year and I don't remember seeeing any fruit last year, was too busy! Noticed it was losing it's leaves. Thought it may be stressed as the water table is very high here and thought it might be waterlogged. It seems to have die back and the leaves have lots of small holes in them. Also spotted a small amount of gum oozing from a couple of the smaller banches. Cut some small branches back and the wood seems to be clean. Is it canker? What should I do next? Have put some photos up to help with diagnosis!