Lip irritation for months - chapped and small red bumps

[imanust]

Since late fall my lips have been a bit of a mess. They are constantly raw feeling and get chapped if I don't use a lip balm every 4 hours or so. I've been to the doctor as well as the dermatologist with no luck. The dermatologist believes it is an allergic reaction to something but was not able to figure it out. I've tried switching just about every possible product that comes into contact with my mouth with no major improvements. The red bumps start out as what looks like a small fluid filled whitehead and are usually gone within a day - they come and go two or three times a week.

See images: http://imgur.com/a/ceTQa

Any help would be awesome! Thank you