I have had something similar to what you describe. The only thing helps me when this happens is Carmex in the little tiny round container. I've had Aquaphor irritate my lips like you mention when I had an 'impending' fever blister brewing. Have you tried taking lysine too? This helps considerably for me, I take about 1,000 mg during the time I have the blister then stop taking it when it goes away. However, if you eat a lot of green leafy veggies like spinach, kale or even avacado that can reactivate the virus responsible for cold sores. Lysine shuts off the other side of the replication pathyway. Be sure to use a lip balm with sunscreen in it b/c UV activates the virus too.