Looks like Ich to me. I would do a water change & start treatment immediately. There are several ich treatments available or you can try to treat with aquarium salt. Melafix & super ick cure have both worked for me in the past. Be careful with salt. ‘Aquarium salt at 3-5 grams/liter for two weeks can be used to treat mild infections of Ich. Be aware that some soft water species and some catfishes can be more sensitive to salt.’ Be sure you are dosing for the correct volume of your tank, not just what is listed as the tank size.
Raise your temperature to at least 80-84°F and start treating the whole tank. I’m sure Colin can provide more detailed assistance.