I'm not an OB nurse..yet, but I do have personal experience with this problem so I wanted to reply. Definitely have your friend see a lactation specialist to make sure she is doing everything correctly first. As long as she is latching correctly I don't think flat nipples matter much in the whole scheme of things ( I have flat nipples too) But the baby should be taking the whole areola in it's mouth. If he's just got the nipple, then I'll bet she is in a world of hurt. What it took for me to get it right was going back to the hospital to see the lactation nurse, who took my nipple and stuffed it in the baby's mouth the right way
She also went over different positions with me and how to tell that my latch was correct. It was very helpful.
Beyond that, plenty of women find it painful to breastfeed for the first few weeks. I know all the books say that it shouldn't hurt if you are doing it right but guess what? The books are wrong! Turn on a 12 amp hoover vacuum and stick the hose end on your bare nipple and tell me that ain't gonna hurt!
When I got to the point where I would cry when I heard my son waking up-- I started calling all the Moms I knew and they ALL told me the same thing, yep- it hurts. They all told me that the pain had lasted 2-4 weeks for them. I felt so much relief at hearing that, I knew that there was an end in sight and that's all it took for me to be able to carry on with what wound up being a very fulfilling thing for my baby and I.
BTW, they were right, the pain went away at the end of week 3. So if your friend is doing everything she should tell her it will get better! In fact it will get great! So don't give up. Breastfeeding IS wonderful, just not in the first weeks
But when she see's that baby getting fatter and knows that it's all coming from her it is the best feeling in the world.
Get her some Lansinoh for her nipples- it really does help to heal them when they are all dry and cracking.