Often swelling and redness in the calf can be caused by cellulitis. This is inflamation caused by bacteria and should be treated immediatelly. First clean the area very well and apply an antibiotic oitment. Oral antibiotics may be needed.
First, keep off of your calf. Then alternate between ice and heat, every 20 minutes, applied to your calf. The combination should reduced the swelling.
Swelling and pain in the calf for no apparent reason could be caused by a blood clot, which can be very dangerous, and deadly if not treated. I recommend seeking medical treatment.