Best option is to speak to the doctor who performed the reconstruction, and if he/she can't help, then they can give you a referral to a doctor that is able to improve your situation. Sometimes massage or intralesional steroids or time can improve a result, but if that is not the case, sometimes revisional surgery or scar revision needs to be performed. Have a doctor who does a lot of nasal reconstruction evaluate your problem.
After a tumor is removed by Mohs surgery, the skin is repaired to minimize scaring and to leave patients with optimal cosmetic and functional results. Occasionally, asymmetry can occur, particularly if the tumor was extensive or located in a complex anatomical area. Massage and local injections of steroids can help relax scar tissue and restore symmetry. This is a good technique if the area is contracted, such as your situation with one nostril being raised higher than the other. If this has been tried and your nostril has remained high, you should ask your doctor if you are a good candidate for scar revision. This is another surgery where the skin of the nose is incised and the scar repositioned to bring the nostril down lower.