Hi Electric W

It sounds like he's had an allergic reaction with this bite .. have you any idea what bit him?
.. if it's penetrated a vein, and it's an insect bite, the small amount of 'venom - poison' has probably reacted with his blood, however as er have given anti-biotics, this will build up anti-bodies against any venom... so make sure he carries on taking them, and go back if it doesn't clear up in the next 7 days..

Any small insect that can penetrate our human skin, has a small (to us) dose of poison or venom .. this is their defensive system against thier prey or preditors ...

I hope all will be better soon, you both take care.. and please get back to us if you need more info ..

good luck and take care

Ginger

I do belive if it were me I'd see a dermotologist IMMEDIATELY or at least get back to the ER......If he is having an allergic reaction, an antibiotic is not gonna help. If these blotches are not decreasing in size, I would not wait for them to double again and something happen...........Hope he gets better soon!