Hi mum2bee.

I had the same thing, but with my right one. Then it started to crack. I asked the midwife/lactation consul. at OB appointment and she suggested Lansinoh or Maracalan. I used maracalan and it was great. Apparently it is our bodies getting ready for breastfeeding. It was all cleared up within a week, and they are both the same as each other now.
Id ask him just in case there is something else wrong though.