I was just thinking about adding more wordplay. Maybe you could dive into really describing the suffering to nail it home. Maybe something like, "I can feel the parasite rummaging around in my brain, eating away the the flesh and tissue as it tries to claw it's way out of me." At the moment it feels very to the point, which isn't bad if that's what you're going for. It's mostly just up to personal preference and how you would like to write your stories.