The doctor gives off an appearance like the 'Invisible Man'. Bandages, Hat, trenchcoat, goggles, gloves, shoes. This is from a distance. Close up, one can see something...shifting...under his clothes. Maybe an arm gets too long. Maybe his torso moves like he has a mass of...something...on his chest. Something alive. Even the bandages sometimes part to show something hairy, or scaly, or some sort of shell. That does not last-because even after that feature changes, it quickly ends and another part of his body is effected.