I woke up this morning with a small bump on the back of my head, right side. the bump is about the size of a mosquito bite. (half a dime) very painful to the touch. hurts when i lay my head down. what could this be?

Inflammation &/or an: Infection. You need an in-person exam by a provider that can lay eyes on it. If it's a hair follicle infection, it's called a furuncle, which, without treatment, can progress to cellulitis &/or abscess. If >1 follicle gets involved, then it's a carbuncle. Talk to your doc about need for drainage, aspiration, culture, empiric antibiotic treatment. If lymphadenitis, use ultrasound & needle biopsy.