Bulge on one side of supratip four months after rhinoplasty, is it swelling?

It is still too early to make a determination about the final result.The nose
can be swollen for up to a year or more. Swelling will depend upon the
nature of maneuvers employed, presence of grafts or implants, thickness
of skin, open vs closed, revision vs primary, etc. Kenneth Hughes, MD Los Angeles, CA

Supratip edema may take a long time to resolve and occasionally benefits from cortisone injections. That said, if the deformity is due to persistent cartilage it may not resolve. Best to follow up with your surgeon to get his opinion.

Irregularities, asymmetries, bulges, etc. can take a long time to go away so wait at least a year before considering revision surgery.  Also, sometimes such swelling is from scar tissue and injection of steroids can be helpful.