Robitussin DM

A
Hi everyone! So I have been fighting with a severe cough for the past almost 2 weeks! It's just KILLING ME! It's affecting me in every way, physical, emotional! 
I am also almost 13 weeks pregnant! I waited and I waited until I decided to go to an Urgent Care and see a doctor! She said it's a severe viral infection! I am coughing day and night, especially at night! Last night it started at 12 until 4 am! I started crying and praying to God to help me! My husband woke up and he didn't know what to do! Everytime I lay down it starts really bad so basically I have to stand up! It's HELL! 
Anyway, the doctor prescribed me Z pack but and Robitussin DM! 
I started the antibiotic which I don't think it will work since it's a very low dosage! 
I started taking Ricola cough drops and those seem to calm me down for the moment! 
When I cough everything hurts, my throat, my lungs, my chest and lately my belly! 
I am really scared and I am looking for some advices! 
Also I am drinking LITERS of water, tea, orange juice! 
Has anyone of you had this and tried any of these medicine? Thank you all and wish you health and healthy babies!