I have pain on the back of my ankle when its moved what could it be? there's little to no swelling

Os Trigonum : Is an extra bone in the back of the ankle and you might have one. Easy to diagnose by x-ray. Could be many other things as well like tendonitis etc.. See a podiatrist for diagnosis and treatment options.

Extra Bone: If without past or present injury, one explanation will be "an extra bone, " of which there are a number in the foot and ankle. Have a doctor take lateral foot views to know, have them taken of both feet. With injury there are rather large tendons right behind your ankle. If we are talking "pins/needles shooting electrical pain" (on the inside of the ankle), consider tarsal tunnel syndrome.