What can I use to heal my lip? Undiagnosed and unresponsive

[IrritatedLip]

A small but definitive localized spot above my lip (philtrum) has been red, flaking, in pain, and at times a little bit itchy since January. It has never fully healed for a long period of time, and has always required some sort of lubricant in order to keep it from drying out, flaking, and turning more red. At times, it looks completely normal....for a few hours or while being medicated. I have consulted multiple doctors and none have been able to prescribe treatment solutions that have helped short- or long- term to effectively address the issue.

My doctor has swabbed the area and the results have come back negative. This was the report: 'No polymorphonuclear cells seen, no squamous epithelial cells seen, no organisms seen'

My doctor had diagnosed as follows:
persistent redness and small pustules on lip, philtrum since January, despite zovirax/caltrex/Hyderm

Over the months, I have also exposed my lip to many different environments with no change in any environment (under safe protective conditions):
1) Extremely hot weather
2) Extremely cold weather
3) Direct sunlight
4) Shade

I have tried the below solutions without addressing the root issue and eliminating the problem - please help!!! Attempted solutions:

1) Tea Tree Oil
2) Vaseline
3) Hydrogen Peroxide
4) Zovirax
5) Bioderm (antibiotic treatment)
6) GM Hyderm Cream 1%
7) Hydrocortisone cream 0.5%
8) Fucidin Ointment 2%
9) Vitamin E 100% pure oil
10) Face cream  (Complex 15, Clinique moisturizing lotion)
11) Nothing on the area at all

What can this issue be? What other possible solutions can I try? I have provided ample time inbetween medications/ointments/creams and even spent weeks without putting anything on at all. The result remains the same: irritated, red, flaky skin that gets inflammed (?) without specific triggers.

I have not put on any creams, lotions, make-up, cleansers, soaps, or anything new that I have not already used for years. Since the irritation, I have stopped using all products in that entire area. I have cleaned with only water and rarely with gentle soap (e.g. after swimming or sunscreen use).

Thank you for your attention, diagnosis, and suggestions for remedies!!

[IrritatedLip]

Anyone?