Male Baldness Info

I usually use a razor blade to shave my head but 2 1/2 months ago i decided to shave my head with a pair of clippers for the 1st time and being the amateur that i am, i accidently nicked a few areas by my left ear & sideburns and was left with a few small bald patches here and there.
A week later as the rest of my hair was growing back those small patches were still bald and i began to worry a little but decided to wait patiently for time to do it’s magic. So flash forward to 2 1/2 months later after i’ve shaved my head again (used a razor blade this time), i can see every hair follicle as clear as day and those bald patches are still there!
What can i do to stimulate hair growth there aside from using rogaine? Would castor oil work? How about a toothbrush?
Please keep in mind that i’m a young adult male with a very full head of hair. So no thinning hair, hair loss, or male pattern baldness to speak of just yet (:

I’ve been shaving my head since 1997, I love to keep it smooth, I however am not suffering from male pattern baldness or anthing like that, I just hate hair or stuble…can any one help?!!!