Pregnant with previous fever, now have rash and swollen hands. What could it be?

Anything. Any rash that you can get when you're not pregnant can also occur in pregnancy; but the fact that you are pregnant means that you must worry about both yourself and your baby. See your doctor asap. The most common cause of your symptoms is probably a virus, but you need to make sure that it is nothing more serious than that.
Concerning. Any fever with a rash could be very concerning during pregnancy and i would contact your gynecologist.