I had cellulitis almost 3weeks ago. they drained it then 5 days later it came back as mrsa. now the wound is about a size of a button. getting better?

Better is good: Because ongoing drainage is important after an abscess is opened, the wound is not sutured closed so will take 3 - 6 weeks to heal depending on size, often longer especially in diabetes. Signs of re-infection include spreading redness, worsening pain, an enlarging mass, thick white/yellow/brown discharge, or fever. Otherwise, a long and gradual course of healing is expected.