Suggest Remedies For A Recurring Red Painful Bump,possible Spider Bite

I belive I had a spider bite me in Southern Queensland, but not sure if it was spider or something else.
I was mountain bike riding in brisbane bush and went through a web, didnt notice any pain until I got home and had a shower and saw a red painfull bump in my groin area about 15mm diameter, I think I opened it cant remember, it is now one year later and I still get a rash come and go that is very sensative and and sometimes painful, it sometimes looks like it is comletely gone and I have no symptoms, but it has recently come back with avengance since moving to china (winter here, so I think the cold or dry air makes it worse)....