How To Treat A Itchy Blister On Feet Due To Possible Insect Bite?

hi, i got bit by something the day before yesterday........and i killed a spider in bed the next morning......now im not sure it was the spider that bit me but anyhow,my foot is extremely itchy and theres a blister formed that has like pus in it...its coming out a little and its soft....(not hot like i read about the poisoness spider bite)
the blister is located right where my foot meets my leg.......on the inside of the angle .....like i said its a blister on top a read circle...slightly raised (from alil scratching n patting, i never go to far)
i have been putting alcahol pads on it after cleaning my feet. Then putting neosporin ...no bandy...been lettin it breath......i have no health insurance at the moment and im really just staying a float so if what i have now will work let me know if you can
thank you
antonio (spider man)