Please help lungs arent working?

Ive been sick for a couple a days and starting today my chest is tight and i've been coughing up yellow phlegm and its reaaallly hard to breathe im about to go to the emergency room and I have really bad panic disorder is it okay to take Ativan or will it shut down my breathing seeing as if I do have pneumonia?? (my dad told me it could do this) but I called the pharmacist and she said its okay