A soft, bubble-like swelling on the back of the head is very common and usually harmless. It is most likely a benign cyst (like a pilar cyst) or a lipoma (a harmless fatty lump). Please avoid squeezing or popping it, as this can cause infection. There are no over-the-counter creams or medicines that will dissolve it. I recommend seeing a doctor for a quick physical exam. If it is a cyst, it can be easily removed through a minor, pain-free outpatient procedure. If it becomes painful, warm, or red, a doctor may prescribe generic antibiotics like cephalexin to treat any underlying infection.