Hi im 22 y/o i have no armpit hairs. and i even notice that if im sweating, my armpits are not which is weird. what to do? need help. thanks..

Unusual!: You may have been born without the glands & follicles that produce sweat and hair. If you sweat normally everywhere else, that's not a problem (actually a blessing!), but you need to check with a doctor to be sure that you don't have an underlying endocrine or sympathetic nervous system problem that somehow stopped hair & sweat glands from developing in that one area.