Congratulations on the arrival of your little boy, and well done for persisting past tge pain so far.

It does sound a bit like it could possibly be vasospasm. I didn't get the characteristic white nipple with mine, just lots of pain and it would turn purple after feeds too. Do you get any pain when you stand in front of the open fridge/a fan/in a cold wind?

I did a few things that really helped and now it's completely under control:
- take evening primrose oil and fish oil - I've continued with this and if I forget for a couple of days it comes back
- buy breastwarmers and wear them in your bra about half hour before feeding (I got mine in a local chemist but I know ABA do them online too)
- always wear breastpads... It's just an extra layer of protection to keep the nipple warm so blood supply will keep flowing
- if you do get pain, cup your hands over your nipples to warm them and protect them from further exposure
- avoid feeding in a draft
- get another lc to look at your attachment, it's so hard to tell whether it's good or not because it always hurts with vasospasm
- check that the attachment you're using on your breastpump is correct for your nipple... Mine was too small and constantly grazed the nipple causing further damage and pain

I hope that helps, and if not that some of the other advice people give you does the trick. Well done and keep up the good work!