Icy hot feeling in nipple?

My left side doesn't stick out very far so my son struggles to latch. I've been using a nipple shield which has really helped, but the first few seconds of him sucking, before his latch is really established, hurts pretty badly. Once he's latched it doesn't hurt anymore. But in between feedings I get this icy hot feeling in my nipple on that side. Has anyone experienced this or knows what it is? I'm assuming it has to do with my son's poor latch on that side but idk what to do to make it any better. 😅