Do you have redness/pimple on the tip of nose? If yes, did you receive an implant during your rhinoplasty?
If no implant was placed during surgery, there is no need to worry. The pimple will go away. However, if an implant was placed this could be implant infection. In that case, antibiotic trial is suggested, which you have already received. Salvaging the implant in this condition will be rather difficult. You may be advised culture specific antibiotics failing which implant removal is the only option.
Once the infection subsides secondary rhinoplasty using autologous tissue such as your own bone or cartilage
can be planned. Stay in touch with your doctor.