Rash On Skin, Develops Scabs. Have Skin Tags. Earlier Bitten By Fly. Why Is This Happening?

I was bitten by a giantormous lol huge dark fly when I was visiting a friend living out in the country outside of the city,I saw a Dr. in the ER in Athabasca,AB he said I was bitten by a horse fly I don t think it was a horse fly,this fly was so big..he said I had an allergic reaction & infection from the bite gave me penicillin took the meds as it said and it went away,now this was in the year 2000..ever since then about every 6-7 months the almost exact bitten spot gets infected,bumps out exactly like when I was bitten it s like a bumpy rash that sometimes when scratched breas the skin open,this goes away in a few days & reappears again 6 months later sometimes are worst than other times but always the same kind of bumpy rash that scabs sometimes,and the spot fly where the fly bit I ve developed a skin tag,almost resembling a tiny nipple , why is this happening & for so many years now? Thank you!