Hi I Started With It Looked Like A Spider Bite

hi i started with it looked like a spider bite at first it felt like a misqeto bite but it swelled up like a pimple but nothing woild come out ane it itched till my skin would bleed my arm swelled p with infection and when it started goimg away another would apear on my foot and itches so bad i scratch till i bleed they look like there starting to get other ones what can it be