I have a bump like a hard small ball form on my inner labia. It has now formed a white head like a pimple. It is sore to the touch but wasn't at first?

Poss. Bartholin inf. This appears to be a possible Bartholin gland infection that may or may not resolve on its own. See a GYN MD if it continues for possible incision and drainage and resolution.
Bartholin cyst. It could be a Bartholin cyst or more likely an abscess. You need to see your doctor as it might need to be drained and you may need antibiotics .