If the abscess is still draining foul smelling discharge, it simply means that the area is still infected and you have to back so that they can do drainage
and dressing with aseptic solutions like betadine
and take other oral antibiotics
order than bactrim such as cloxacillin
which are much more effective in dermal infections. Daily dressing has to be done till the abscess is no longer discharging any foul smelling or colored fluid. Serous fluid discharge (mildly) is acceptable and redness of the wound shows sign of proper healing and absence of serious bacterial infection.
Thanks and hope this helps