My bodys skin tone changes..... 1 day it's fairer and 1 day it becomes darker... This cycle change every 3-5 days...What to do....... I'm 19 yr boy....

From the sunshine? Naturally dark skin is genetically determined, and runs in the family. A person gets darker after being in the sun, and lighter when out of the sun. If one is the same color as one's parents, siblings, and other relatives in the racial group, then one's color is most likely normal. If one is much darker than other family members, then a primary care doctor can evaluate for a hormonal problem.