Flu like symtoms after a heavy night drinking..?

I went out for my 21st this weekend past and lets just say I had a lot to drink. Now 2 days on I am lethargic with a low grade fever body aches runny nose loss of appitite nausea and a mive head ache... these are 2 full days after I drank and it feels lke someones punched me in the vercinity of my liver. Can anyone tell me what's going on? Is it just a virus or is it worse. Cheers