It does sound a bit like a latch problem. You've got to get that nipple deeply into the baby's mouth, so he or she won't gum it. Did you take a breastfeeding class last time or talk to a lactation consultant?
You could try going braless in a rough cotton shirt for a while, it might help toughen up your nipples.
The thing that worked best for me was the 100% pure lanolin they sell at the baby stores. It heals the nipples fast.
My breastfeeding instructor also suggested taking a standard tea (like Lipton's) and putting about 8 teabags into a cup and making one cup of concentrated tea, then putting that concentrate into a jar and saving it in the fridge to dab on the nipples with cotton balls. Don't know why it soothes, maybe it's the tannic acid or something.
Thank you for that advice. I'll definitely be giving that position a try!
Sometimes if u change your hold it can help. Try the lay back position so u r laying back but not flat on ur back and have the baby on top of u so he can latch. It helped me a lot last time.