Cyst or not? Need your help

Hi, on my sternum, there is now a small lump, dead center between the breasts. I noticed it probably 6 yrs ago. At that time, it looked more like a pimple without redness or swelling. Every so often I could squeeze this white stuff out. Then it would look smaller, but red and irritated. The irritation would leave in a couple days. Time would pass, it would get my attention again, and I'd repeat the process. I am not able to 'get a hold of it' anymore, it is in a position where it just is not easy to grasp, it slips, I would describe it more as a lump now. Because I try to fool with it, there is now soreness, not red, or draining, it no longer appears to have an opening, yet I may be able to discern a tiny indentation where I used to be able to squeeze white stuff from. Is this what you all are calling a seb. cyst? If it is your opionion that it is, what is the most effective way to clear it....thanks Tweet