dog skin disease

Question
i have a 2 yr.,male, black lab that has developed a patch of irritated skin on his left,upper hind qtr. next to the spine and tail.  it started as a 1/2 dollar size and now has enlarged, due to the dog licking it, to 3"-4" size.  another man called it a "hot spot"'  i have treated with a wound protector and a ointment. my research indicates it could be either "ringworm" or "mange". what is the disease and the cause?  
how or what can be used to treat it?  any suggestions will be appreciated.  

Answer
If it is a hot spot, then it needs to be treated with a shot of a steroid to take away the inflammation and weeping from the wound.  If it is ringworm, a culture should be done and if it is mange, it needs to be scraped and confirmed.  Treatment will depend on the diagnosis.  Ask your vet for help.