Is it a skin ulcer or something else-I hope?

My friend has developed something on her leg that looks like a scratch. I have fears and suspicions that it may be a skin ulcer. Please tell me what the symptoms are and if the symptoms include stinging and itching of the affected site. She uses hydrogen peroxide to cleanse the area and Neosporin to try and get it to heal and keep it free of infection. Please help, I am very concerned about her.