My name is Shannen, I'm a feline behaviorist and can definitely help you with this problem!
Assuming the vet has cleared him of any other health problems that could cause this sudden change of behavior, I'd actually assume he is acting this way because he is feeling better and more lively, which is a good thing!
But, it could be beneficial to work on some training and practices that will help with some more self-control. Here are some general ideas to start!
- How old is he now? Getting him neutered can definitely help with some of the issues you've been having. It won't be a quick fix, but being intact can contribute to lack of self-control.
- Kittens need about 1-2 hours of strenuous exercise and playtime a day, so make sure you're meeting those goals each day!
-If you consulted with your vet that you're giving the right amount of food, changing the food can sometimes help as well. What type of food do you feed him?
- Kittens will easily become bored and it looks like your counters and tv fell victim! Keep your kitten stimulated by cycling out different interactive toys, puzzle toys, etc.
- If he's treat-motivated, use this to your advantage! Each time he goes on the counter, tell him off, and direct him to get off the counter using the treat, and have him jump onto another high surface, like a cat tree!
Try some of these tips and let me know how it goes!