Suggest Medication For Congestion, Cough With Mucus And Allergy

I have allergy plus a cough with mucus. I had taken Claritin-D 24 hrs ( kirkland brand) with mucinexDM but I could not sleep because of the coughing at nite. I think thr mucinexDM did help with the de congestion. I went to talk to a phamarcist who told me it is the Decongestant that kept me awake? Is this right?