This is not a big deal, ...yet. I see the infection but no froth exudate from the nostrils. The infection appears to be topical at this time.
Keep the temp at 84-85F. Add sea mix salt to light brackish levels (spec. grav: 1.002-1.004). Add Maroxy at full dose (this med is safe enough for treating fish eggs). Then, just wait for everything to work. Continue treatment for a week after the last trace of fungal infection has disappeared.
Then, water change and maintain temp at 82F-84F for this species. Also keep the water slightly brackish and alkaline (with bulk limestone and/or aragonite).
This species will occassionally slough the surface of their leathery carapace. Don't freak out if you see this. It's their way of replacing a damaged surface layer.