I have a bumb on my stomach started out small like a mosquito bite and has gottten bigger area around it is red and sore/ tender hurts when i move not?

Cellulitis: Redness of the skin that is spreading out from a bite or wound that is warm or tender could be Cellulitis. You should see a doctor to get started on antibiotics. http://www.healthline.com/health/cellulitis

Infection: Sounds like this bite is actually an infection of the skin - called an abscess. If it is red, hot, hard and painful, it is time to have it looked at by a doctor or provider who can drain the pus out. Often, drainage of the pus plus an antibiotic is needed for skin abscesses.