Hello
Welcome to health care magic.
Pus filled lesions at bite site of spider indicates secondary bacterial infection of skin.
If I were your treating doctor,I recommend,
-Local application of antibiotic ointment like fusiderm thrice a day for 3 days.
-Oral antihistaminics like
cetrizine once daily for 3 days for rash.
-If the lesion donot subside,
oral antibiotics course may be needed with cipro/
cephalexin for 5-7 days for which you need to visit physician/
dermatologist.Also the possibility of shingles need to be rule out from medical history and local examination..
Hope I answered your query.
Feel free to ask any more if you have.