I was stung by a wasp today on my hand. It's been seven hours and its red, hot and swollen. It itches a lot. I never remember a stng being so swollen?

Wasp. Take some antihistamines such as Allegra (fexofenadine). Your physician may also prescribe you a short course of steroids.
Insect bite. It is not unusual to have swelling and feeling hot. It shows more especially if it is on the back of your hands. It will subside with time. Icing and anti histamine and anti inflammatory medicine might help.