Protrusion from Columella into One Nostril After Rhinoplasty

In my opinion, 99.99 times out of 100, nostril asymmetry is from the caudal septum. Yours probably needs to be trimmed back since it is too long for the new shape of your nose. Usually that can be done, unless a large resection of septal cartilage was done in the original operation. 1 cm of undisturbed cartilage needs to be present in that area in order to ensure support for the rest of your nose.
If that is the problem and you have enough cartilage, then it is a minor procedure compared to the original operation.
Good luck

From the appearance of the photograph, it looks as if your caudal septum (the lowest portion) is displaced into the nostril.  This can be reduced and trimmed to correct the problem.

Based on the description provided, this appears to be swelling along the incision line on the left side. Most rhinoplasty surgeons make the septoplasty incision on the left side. Whichever incision was performed on the side harvesting septal cartilage will be more swollen. Occasionally where the sutures were placed on the columella, this can be pulled apart on a temporary basis and will resolve over time. It tends to be more swollen on one side versus the other. This will most likely settle down on its own in the next two weeks.