i had vasospasm (and a raynaulds white finger) which started when i was pregnant - although didn't realise that it was even possible for this to happen - i just thought it was bitterly cold and that made it bitterly painful.
when it happened the end of the nipple went white and literally cold to the touch, and very very painful. but it went completely back to normal when the episode passed.
i would agree with the keeping it warm method, if you find a technique that works for you, make sure it is warm before you start a feed, as i don't think it helps to try to latch the baby on while it is painful. don't know if it has any effect on milk flow though.
i tended to just use the palm of my hand, and it wasn't long before it passed, or get in a hot shower. and for generally keeping warm while feeding in chilly times / places, i wore a boob tube under my bust-well down over my belly-and tucked in to trousers, and a thermal base layer (thin ski-type garment)
cardigan on hand for night feeds - and learning to feed lying down helped a lot with cold and tired night feeds. i kept baby in moses basket right next to bed - which was nearly as good as co-sleeping.
if DH feels the need to comment on attractiveness of night attire, suggest that you ice his nipple until it is numb, then pinch it really hard. or maybe not - that might not help ;)
i had various other problems with attachment which also caused feeding to be painful - up until about 14 weeks.
the plus side is that i haven't had it happen for AGES. i couldn't tell you when it last happened.
when your baby clamps down- put a finger in the side of their mouth to remove them immediately, and (easier said than done) calmly but firmly tell them 'no biting'. sometimes when my baby did this, i could see that my nipple had gone white - so maybe she was complaining about the milk stopping - but i think you do have to get them to understand that biting (or gumming) is not ok. i'm glad she got the message particularly as she now has 6 teeth!
it might help if you can get someone to check your attachment while you feed - or just to have a check that there isn't anything else that could be causing you pain.
feel free to ignore the mother - do what is right for you and your baby!
hope this helps cardicorgi