Bitten yesterday, small lump, has spread 2 6cm red burning pattern. gp said spider bite, cortisone, telfast &ice. no improvement?

Spider bite: If this in fact was a spider bite, the two are the black widow, and the more common brown spider. The latter has a very toxic poison which damages tissue and often requires surgical excision of tissues. No surprising that you are not seeing improvement. You might want to contact a general or plastic surgeon who is familiar with this issue. Good luck and best wishes for a good outcome.