I Had Boil For About 21/2 Months. Stubbornly, I Went

I had boil for about 21/2 months. Stubbornly, I went to the doctors and prescribed bacterium for ten days. One pill a day. It began to shrink but the dosage was either not long enough or strong enough. It grew back. I went back to doctors today and was prescribed 500mg. Four a day for ten days. Apparently I did some research and it is none effective against MSRA. I wasn't diagnosed with MSRA but is it possible o was mis diagnosed. If it's just a boil will the Cephalexin work??