Try this to treat a clogged duct:
Rub and massage the area while in a warm shower or bath. Apply moist hot packs to your breast. The heat enables the milk duct to open better and allows for better milk drainage. Use massage and heat on the affected side while you breastfeed. After applying heat and your breast is still warm, massage from your armpit down to your nipple. Avoid putting pressure on one area of the breast for an length of time and wear a comfortable and well fitted bra. Get enough rest, which may be impossible to do due to the pain.
Try to remove the milk plug. It is safe to squeeze out the milk plug as long as it is done gently and hygienically. It is sometimes possible to massage the affected breast until a white head at the end appears at the end of a duct on your nipple. Apply moist heat and carefully pop the blister with a sterile needle. By gently squeezing, you will unplug the nipple opening. You may need to use an antibiotic ointment for a few days to prevent infection.
If the plugged duct persists and is accompanied by additional symptoms, it may be a sign of an infection that requires medical treament. Call your doctor if you experience fever for 24 hours, sudden onset of chills, general feeling of being sick, or nausea. Most plugged ducts will go away within a couple of days without developing into mastitis if treated promptly. If the milk flows freely through the ducts, bacteria is flushed out. However, if it doesn't, this may allow bacteria to grow. That's why your first step in treating a plugged duct is to empty your breast frequently and completely. If an infection develops, your doctor may prescribe you antibotics.
Hope this helps. I've been there before.