Then i suspect it´s WC, which is bad news for you (and for the animal and the species...). They are very prone to skin infections, so you need to make sure you are providing the adequate humidity, and ventilation, and most of all the right temperature. Avoid stressing it, do not touch! Keep it in a shady, quiet place.
If the problem persists, then as Kurt says, a visit to the vet is in order.

Also, make sure you read the article in my previous response, it´s full of excelent info. It sounds like your housing conditions are far from ideal, so you might want to revisit the husbandry. Also, if possible, please post a picture of the tank and the salamander, it will help a great deal in mending possible problems.