Could be aphids? Do you see a lot of ants running around all over the tree? How about green aphids on the underside of the leaves?

Unroll those leaves and see if you can find a caterpillar anywhere in there. Little black dots I believe would be frass, not eggs.

You were right. After opening several leaves I found this small caterpillar. Can I do anything to treat the tree this year? And prevention next year?5

Those leaf rollers/folders are moth caterpillars, so BT will be effective now or next year.

You can simply remove rolled leaves, if there are merely dozens or a couple hundred of them and they are within reach.

Just swipe your thumb through each leaf and squish the caterpillars. They are hard to control because the BT or other spray doesn't penetrate well inside the rolled up leaf.

They will damage the fruit where they web up against the fruits surface. Just surface feeders but makes a mess of things.