Nipple red??

So

For the past few days my left nipple has been in bad pain i thought because my babys teeth are grazing when nursing (i always feed that side first bc its my super slow side). But just today i noticed that nipple is red whereas my right nipple is normal. Theres no sign of plugged duct or mastitis.

Anyone have an idea whats going on?? Could it be bc of his teeth?