I think you are on the right track with this. I suspect an autoimmune disease stemming from gut issues, in my case.
I notice a direct correlation between how my lips are on a very basic diet versus mixing in lots of foods with loads of different ingredients. A trigger may be in the form of a flare up of my psoriasis/dermatitis around my face and a sore/sticky red inflammation on the inside of the lips followed by peeling/drying cycles on the outer lip (EC).
I am still suffering inflammation but my god it is reducing so long as I stick to basic fruits and vegetables. If I use cooking oils it will either be virgin olive oil or coconut oil. I have made a total overhaul to my diet and I am seeing subtle changes in the peeling.
I would also question these Antibiotic drugs that wipe out all of the gut flora (good as well as bad) - surely this cannot be a good thing, hence why they come with so many warnings.
The best approach is to aid the body in eliminating bad bacteria whilst nourishing the good. The bodies natural state is that of equilibrium, all we have to do is eat the right foods that do this, and not heavily laden toxic foods that disturb the gut and cause the normal autoimmune response to go into overdrive, attacking healthy tissue and cells.