Hi, my upper lip (above lip,below nose) color getting change now it's like black pigmentation, I'm i pregnant?

First i thought it was due to small hair but today i noticed there is no hair is growing but still it is looking dark, i'm little fair so this dark color on my upper lip looking worst I'm house wife and i never walk out during sunlight and past 1 week i feel so hungry, leg pain, stomach pain also i feel difficult when i sit and stand because of pain today my period due i took home pregnancy test it came out as negative ,,, so i'm just wondering i'm pregnant or not...upper lip discoloration is due to pregnancy or for some other reason