Difference between crabs and razor rash?

Pubic Lice vs razor: Rash. Blue spots may show on the skin where pubic lice (phthirus pubis )have been feeding. Nits (eggs) may be found on the pubic hairs. The lice’s saliva can cause a person to become very itchy, which is usually worse at night. Sores can develop when the skin is scratched.**razor burn can occur after shaving. The skin becomes red ; inflamed ; may sting or itch.