It sounds like you have a phenol sensitivity, as do I. Phenols are substances that are in almost all foods, but in varying amounts. If I eat a high phenol/salicylate fruit I have the same reaction. After a short delay of about a day, my lips swell up a bit, turn blood red, and I feel them 'burn', or as I think of it 'pins and needles'. All of this lasts for a few days to a week, after which my lips are dry and cracking. It's usually related to foods, In my case at least. Here's some links to help you out:
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Since I can't post links, just remove the spaces.
Phenols - Wikipedia, the free encyclopedia - What the chemical is.
Dana's View - Phenol Information - An overview of it. I suggest you start here.
Food Salicylate Content List - Very helpful list of foods and their relative Salicylate amounts.
I'd look at the list of Salicylatic foods and try and remember if you've eaten any of them prior to the reaction.
As for treatment, and I'm no doctor, but an anti-histamine like benadryl should shorten the whole cycle. I usually do this and drink a whole lot of water, which seems to help. I haven't had any luck with chapsticks or vaseline myself, but you can keep trying them.
Anyway, after this entire cycle my lips are back to normal. This might happen in your case if you do in fact have a phenol sensitivity. Again, I'm no doctor, but that's what happens to me. Best of luck figuring out what it is!