Whats wrong with my puppy?

I have a 5 month old chihuahua and a few weeks ago i noticed she had a little bloody knot inside her ear that was healing and it hurt when i tried to touch it. After it healed it appear again in her neck and behind her ear this one doesn't hurt when i touch it. Im sure when those wounds heal a new one is going to appear in another part of her body. It happened to another chihuahua that i had a few years ago ( they were not related ) im just wondering if its some kind of topical infection or mildew, mold, yeast. PLEASE HELP