I used to shave a lot but less now because i noticed that i began to have these red and black bumps all over my legs. what can i do to eradicate them?

Time to recover: Avoid shaving for awhile, and apply a good moisturizing cream to the skin of your legs, regularly, especially immediately after bathing. Allow some time for your skin to recover. The response you are having is not uncommon, especially in women with sensitive skin. If you are going to shave, use a moisturizing gel/foam when you do.

Dermatologist maybe: Since the bumps are already there, consider applying the acne blemish medication, Benzoyl peroxide 2.5% or an aloe containing skin lotion. If persisting see a Dermatologist. For future prevention of bumps, moisten legs by soaking them in bath water first or apply some moisturizing lotion to the shaving area plus use fresh razors made for sensitive skin