Have you tried putting the medicine on a pecan half in the grooves? When I have squirrels that are difficult to get medicine in, I will put the medicine on a pecan half, put it in the fridge to let it dry on it, and then put a dab of peanut butter on top once the medicine has dried on it. It is a little difficult sometimes to get all of it to stay on the pecan, so I will put a tiny amount of peanut butter on both ends of the pecan before putting the meds on it so that the medicine doesn't go running out of the ends. Hope you can find a way to get the meds in your little guy.. I'm sure he is in pain.