Okay. Don't panic. Panic will just make it worse. You stifle the scream rising in your throat, forcing yourself to take deep, slow breaths. You pull your other leg away from the infected one, turning it over to check for growth. Good, no fungus on that one. You pull it out of the water, up against your chest. Now, how are you going to get this stuff off? Touching it will just get it on your hands. If only you had...
Of course!
You grab your backpack, pulling out a pair of leather gloves and slipping them on. Good. Now you can clean off the infection safely. But how? You rifle through your backpack, trying to find something useful. Pocket knife? Hell no. You can't cut it off. It feels like normal skin, like there's nothing on there at all. Must be why you didn't notice it sooner. You'd probably bleed out if you tried that. Water purifying tablets? Maybe. They kill microbes and fungus after all. But they take time. Need something faster too.
Ah, there you go. Soap and a bristle brush. You lather it up and go to town on your foot. The moment the bristles make contact, the fungus comes alive on your skin, sprouting thin tendrils that try to grab at your hands, but find no purchase on the leather gloves. It writhes and screeches as the brush scrapes it away from your skin. You're making headway now. The fungus folds in on itself, letting go of your ankle as it grabs onto the brush with surprising strength. It's wrapping tendrils around your toes for purchase as it struggles, giving up its grip on the rest of your foot. You grab at the tendrils with your free hand, tearing them free one by one. They float limply from your foot, like streamers in the water's current. You've almost won!
And that's when a trout decides to come and see what's going on.