Trying frantically to think of anything that might stop this slow invasion, you remember the old trick that they always used in the movies. When they'd get poisoned, they always just tied it off, and it stopped the poison from progressing. Maybe the same works for a latex infection?
Deciding that anything is better than doing nothing, you limp back to your room, unaccustomed to walking with a cat's paw... er, foot... er, thing on one leg and a human foot on the other. By the time you make it there, the swelling and blackness has only made it halfway up to your knee, but it's still progressing slowly but surely. Grabbing a shirt, you tear it open, fashioning a crude cloth out of it, and then tie it as tightly as you can just below your knee. Having done this, you can only sit and wait to see if your plan works. You watch as that bulging latex makes its way up your shin, the steady march of shiny blackness moving constantly upwards. After what seems like an eternity, it finally reaches the "cloth", and just below it you can see the swelling intensifying. You feel an intense pain as your flesh expands well beyond its natural limits, the latex look flushing into it far faster than before as the substance tries to push its way past your makeshift barrier. Just as the pain approaches excruciating, you can see the dam you've made starting to fail, its fabric slowly coming apart at the seams, unraveling in the face of this immense pressure. You might not be able to take this much longer...
Suddenly, without warning, the bulge bursts downwards, shooting out of the small bite mark in your heel that (until now) had been indistinguishable from the rest of your leg with the force of a fire hose. You're almost knocked right over as the thick black ooze launches across the room and splatters on the wall, gathering into an unmoving puddle on the floor. At the same time, you not only feel a relief from all of that pressure, but even feel the cloth starting to slip as the swelling in your lower leg goes down enough for it to match the rest of it. Looking at it, you're dismayed to find that it's still covered in black latex, that cat's foot still at its base, but you can see a clear line where the latex ends and your skin begins just below your knee and it no longer appears to be spreading.
Things could be worse, you reason, climbing to your feet and starting to make your way out of your room. As you exit the door, you look back... only to find that black latex puddle absent. No doubt, it waits to ambush you and finish the job that it's started.