If it is a lump that keeps breaking open I would recommend taking him in a for an exam. They can look at the stuff that is coming out under the microscope and see if it has any signs of infection. Sometimes the exudate can look like just blood, but will have a lot of white blood cells and bacteria indicating infection. But then they can tell you if it is just a sebaceous cyst. If it is that, then you can either deal with it opening from time to time and draining or think about having it removed surgically.
Continue to clean it daily with antibacteria soap and water and apply neosporin daily if you don't plan on taking him in. Now that it is open and draining he can easily get an infection in that area.