I have these bumps on my buttocks and thighs that hurt to the touch and are filled with pus. What could it be?

FOLLICULITIS. Dear chris, this condition you describe in brief may be a skin infection caused by staphyloccocal bacteria. I suggest you see your primary care physician asap and have him/her examine the outbreak. If it is bacterial in etiology you will need antibiotic therapy and possibly topical antibiotic therapy to rid yourself of this miserable soundy malady.