Hello, i have a large (what i think is) a pimple). it resembles a whitehead. yet it is large and is lasting a few weeks. it is on my outer right thigh?

Could be a boil: Most pimples, boils or abscesses get larger and are red and painful. They do not typically last a few weeks but it could be. I would use a warm compress several times each day to bring to a head and ultimately drain. If it does not drain or improve your really need to see a provider so it can be evaluated and opened, cultured and treated if it is a boil. Don't wait on this it can be serious.

Cyst: Likely an inclusion cyst on your thigh. Leave it alone, see your doctor for removal.