Me:
I've been thinking about this for a few days, but if Rocket got sick, do you think he would need to see a vet or a regular doctor? Or someone else entirely? Do you think he can get sick? (Obviously, he can get injured, we saw, but that's different) do you think he's had to self-teach how to get over sicknesses? Do you think there are foods he couldn't eat? Or maybe because he's enhanced his diet would be more similar to a humanoid?
Practically-an-x-man:
Hm… let me think about this for a minute
Raccoons are already omnivores, so I don't think his diet would be too different from a human/humanoid. He might have to consume more protein and fewer carbohydrates, so probably more meat and stuff than bread or pasta, but overall it would be similar
He's a scientifically-enhanced raccoon, not an alien species, so my gut says vet. But on the other hand, doctors in space are probably used to dealing with various aliens with different physiology, so they could probably treat him anyway. There are probably different doctors specializing in humanoid, animalistic, or even mineral aliens like Korg, the same way Earth doctors have specializations for kids, elderly people, or specific conditions/body systems
He probably still has taught himself to get over sicknesses, but I'd imagine that's more because he'd be uncomfortable with doctors than because those doctors couldn't treat him