I got sore nipples too when i nursed my baby. I got it at 2 weeks after i breastfeed my gal. i did not consult any LC, i just apply my breast milk every hourly and soon it will recover.
should let the baby sucks for 15 mins, then change to the other side and sucks for 15 mins. Keep Alternate the breast until the baby stop sucking, but sometime the baby will fall asleep when you change to the other side of the breast. Then you may wanna wake them up continue to feed them.