hello, miconazole is antifungal and as u stated you had herpes labialis.. which if at all require the application of antiviral agents like acyclovir.. you should stop using it as it may have got superinfection by some bacteria.. just apply a layer of plain lip-gel on the lesion.. take multi-vits supplement for faster healing.. nothing can be done untill clinical examination... if its still viral infection it will heal up in next 7 days.. you can also go for biopsy of the fluid filled vesicle..which will help in assessing nature of infection and its treatment plan.. have good diet with plenty of raw fruits and veggies, as viral infections are common in immunucompromised patients.. clean your lips regularly and if it doesnt show improvement in 3 days consult oral medicine specialist for antiviral /antibacterial ointments as required.. take care..