Hi.. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concerns.. As per your complain it Rash over the lip along with dry chapped lips and a film over the lips as well as blisters can be due to causes like Fungal infection, Viral infection like Herpes causing Cold Sores while can also be due to allergic reaction to some unknown allergen.. I would suggest you to consult a Dermatologist and get evaluated and a clinical evaluation and investigations like micorscopic examination from the scraping from the lip as well as Biopsy can help in diagnosis and treatment can be done accordingly.. You can be given treatment like anti Viral Oral and topical Medication like Acyclovir, Valacyclovir in case of Herpes.. Antifungal medicines like Fluconazole, Miconazole etc can be given in case of fungal infection.. Anti allergics can be advised for allergies along with ruling out the allergens and avoid exposure to the same for reducing the recurring symptoms. You should also apply thick coat of Petroleum jelly over the lips.. Drink plenty of water.. Avoid application of any harsh chemical cosmetics.. Limit sun exposure . Hope this information helps.. Thanks and regards. Dr.Honey Nandwani Arora.