My advice would be to see a doctor so they can identify the microorganism. If you got yellow pus, ALMOST always indicates some staphylococcus aureus. Other cases are due to Streptococcus pyogenes or E. coli. As far as the antibiotic goes, a penicillinase-resistant penicillin. (Augementin) If you dont have pus, antibiotic should be fine...but if you do have pus, drainage is necessary. My .02.