Drug dependency with L-hist mont tablet.

I have allergic rhinitis(severe cold), asthma and sinusitis. One ENT doctor suggested L-hist mont tablet for allergy and antibiotic (Amoxicillin with potassium clavulanate) for sinus infections. She told I have to use anti histamine tablet for life long for my allergy (not lying). My symptoms (runny nose, itchy eyes, pain in frontal and maxillary sinus, wheezing soun and post nasal drip) will be in control only if I use the L-hist tablet. Now a days when I miss the dose, I am getting skin rashes and acne on my skin (this is not there for me in past). Is it due to drug dependency of my body with L-hist? If so can I control that? What should be my course of action now? I have been using L-hist since 4 years and seroflo 250mg rotacaps for asthma since 7 years. When I miss inhaler i will get only asthma symptoms. But y missing L-hist is causing a new symptom which I am not at all effected in past?