I have a lump that's growing larger on my upper left hairline. any help with this diagnosis?

Get checked: Depends on the growth rate. Typically these will be sebacious cysts, which are benign, but you should have your doctor check it.

Get it seen: It needs to be seen since any growing mass might be a dangerous tumor. Most often these scalp lesions are epidermoid inclusion cysts, and you probably want this removed for looks and convenience -- you don't want it getting bumped or perhaps rupturing. Best of luck.