A big black hornet stung my arm in a vicious insect attack last Thursday and the crimson welt has not gone down. The rash is itchy and hasn't gone away despite my taking antihistamines.

I picked at the wound with a needle to try and get rid of the sting but that hasn't helped either.

How long can I expect the symptoms to last? I'm going to the doctors on Friday but any tips or reassurance until them would be very welcome!