First, let me say it would have been easier for me ifyou'd responded under your original question, as if you were answering it yourself. Asking a separate question meant I had to go to your profile page, select the previous question, re read it, then come back to this question to answer you, so next time, put your response under other responses, i.e., if you want to say something in answer to this, add it below by clicking in the box - anyone who's answered will get a notification that something's been added and can have a look at it.

No, nothing you can do to save the fruit this year, those which have been penetrated by moth larvae will remain so. Does sound like Plum Moth - buy yourself a pheremone trap for Plum Moth and erect it at the right time (think its Spring, but check) according to the instructions. If you have only one plum tree, this should be enough to protect the tree on its own, but at the very least, it should display when is the correct time to spray the tree (no easy task). Also next year, don't feed it tomato food. Assuming it's in the ground, apply Vitax Q4 around the roots in Spring, and cover with a thinnish layer of something humus rich such as well rotted compost or garden compost or soil conditioning compost from the garden centre. Do not pile it up around the trunk, just spread around it. Should be done when the soil is moist, not dry. During hot dry spells, make sure the tree gets 2 gallons of water a week as a minimum once the fruitlets form.