Remember, the skill is called "Puppet Master". I think whenever he uses the skill on himself, it's not only upping his senses, speed and strength, it's slightly being influenced by some outside force.
After we see him first use the skill on himself, we see some dark entity speaking that unknown language towards him.
Whatever that entity is it's encouraging him, even sabotaging his body to use the skill even more.
I was thinking something similar. I don't really think there is someone controlling him though; he's the one calling the technique puppet master.
It was explained much earlier that enchantments could have drawbacks and that brain enchantments were forbidden because of how dangerous they were. And while he thinks he's avoided most damage, he's clearly not well.
We learned a few chapters ago that the labyrinth's boundaries are all enchanted. We don't know what the labyrinth itself is, but it is a place where the strong can challenge themselves. I've started to think that his psychosis is related to him using enchantments on his brain and somehow getting on the same frequency of the enchantments of the labyrinth, which has led to these instructions getting imprinted on his brain. He doesn't quite understand the language itself, but the more he uses puppet master, the more in tune he gets.
Unfortunately, since his brain has already been modified, his psychosis is affecting him at all times. He's going to have to lobotomise himself or find a way to enchant his brain to remove whatever is creating those urges, if he ever gets to understand the labyrinth's structure. Maybe just beating the labyrinth might be sufficient.
I wonder if the labyrinth monsters, who might have originally just been regular beasts from another continent (at least according to the theory made by minerva) are also similarly enchanted, which is what makes them so powerful, but also compelled to fight. In other words, I wonder if he's tapped into the same enchantments that was meant to make the monsters tick.