Plum tree

[AnnieD]

Hi all,
I've got a small plum tree in its third year, and for the first time I have loads of small fruit forming.
But today I was distressed to see that something is wrong with the leaves. They are curling up and looking diseased. I'm not sure if it's frost damage or a pest. I have googled but can't find any useful information.
Can anyone advise what might be causing this? Would a picture help? (I forgot to take one today)
I have so far managed without using any chemicals on my plot, but I would be willing to use something just on this tree to save my plums.

[AnnieD]

[Tee Gee]

Is your leaf curling anything like this;

https://www.rhs.org.uk/Advice/Profile?PID=681

[AnnieD]

Is your leaf curling anything like this;

https://www.rhs.org.uk/Advice/Profile?PID=681

Yes, a bit, but browner., and more folded up. I did spray with some of my whitefly spray, as that's all I had. Will see tomorrow if it's got any worse..