Could a space heater near your feet be causing a rash? Lots of people who keep a space heater under their desk find that their legs get itchy and develop red bumps.  They can be in one place, or all over the legs and feet.

This is probably heat rash, which is caused by excessive heat on or near the skin.  Heat rash will generally go away on it's own, as long as you move the heater away from you.  If it doesn't, you should check with your doctor.

There's some other great information on heat rash at the Mayo Clinic