Just noticed today we have exactly the same thing on our plum trees. We were wondering if it was cold wind damage to the young soft leaves, from a week or so back. it looks as if there is new leaf growth at the tips, which is what has happened in some years previously after there's been some vicious wind. When the leaves shrivel then the tree can't support fruit.
I think maybe the aphids move in after the initial damage has happened, and hide under the crinkled leaves, reproducing horribly quickly.