Antibiotics/Robitussion

Hi, I need some help. I am currently on antibiotics from having a really bad cold for three weeks and my doctor gave me antibiotics for 13 days. I am also taking prenatal vitamins. My ovulation is coming up Thursday and my husband comes back from work on Wednesday. Is it okay to take robitussin too to help thin my cervical mucus? I have never tried the Robitussin and still researching. Have any of you amazing ladies tried this and have success?