I have a lump under my skin on my left side of my face along my jaw line and i don't know what it is. i've had it for months and im only 18.

Need exam: The most common growths that present as a lump as you have described include lipomas (fatty growth) and epidermal inclusion cyst (skin cyst). Less common and potentially more serious possibilities exist and need to be excluded as possibilities . The best way to do that is visit your primary care doctor or dermatologist and have your lump evaluated.