I Have Had Cancer Three Times A Hysterectomy, A Full

I have had cancer three times a hysterectomy, a full mastectomy and a partial mastectomy.. A mammogram just found another new nodule. It is very small. I want a full mastectomy to stop the constant worry that I have every day of my life. All my cancers hurt so every pain becomes a major fear. BUT I only have medicare. Will that cover a full mastectomy if the nodule is small? I don't want another partial and still have the non stop worry.