Hi Joey,
Most of these lesions are caused by bacteria/fungi (saprolegnia) or even algae and usually these are secondary infections of wounds (the possibility of this being a bite from another tank mate is very high).
Nevertheless, it could have other causes (although much less common) like facial abrasions (from rubbing the face on the glass), neopasia (like fibroma) or even chemical burns from high ammonia concentration in the water. It could also been bitten by some live prey.
First of all check the water pH and ammonia/nitrites/nitrates concentration. As a preventive measure put this animal in a quarantine tank with very clean aged water and start salt baths once daily (remember it will only acts against fungi and some bacteria). You can also apply some local desinfectant (there are a number that are safe in amphibians, just check some other posts).
I should also advise you to look for veterinary help because although this might look a common fungal/bacterial infection you may be dealing with some other problem which will be needing some special diagnosis (like citology/biopsy, culture) or treatment.
Hope this helps!
Filipe