What Causes Blisters On Skin After Taking Treatment For Spider Bite?

Bitten by unknown type spideron little toe 24/12/10. Had reaction all over skin looked like measles. treated in emergency dept with two tablets. cant remember names. (sorry)went to gp two weeks later with tinnea type degradation around bite site. local area rednness two toes in. prescribed nystatin500,00lu and hydrozole cream. Still small local blisters keep forming. Are the drugs i took for tinnea or something more serious. should i take another course or see doctor before. repeating nilstat and applying more cortisone creams.