After using methamphetamine regularly for 4 years by snorting method, what is the possible damage done to the nose and how might one experience these effects?

Septum perforation: Have you stopped doing meth? If not do that first. Seek counseling if you cannot do it on your own. Meth use can cause death of part of the nose tissue resulting in a hole in the septum separating the two sides of the nose. Have a healthy diet, exercise 30 minutes/day, drink plenty of water, have safe sex, no tobacco alcohol weed or street drugs. For nutrition: http://www.choosemyplate.gov/.