Is it possible that the medicine is the problem?

Okay, I got diagnosed with bronchitis yesterday but three days ago I took robitussin and two days ago started getting hives. Yesterday they slowed down (probably because I didn't take any robitussin that morning) but I got prescribed cheratussin along with a z pack thing and I took the cheratussin about midday and they came back and I took it again 4 hours later, then it hit me that the cough syrup was probably the cause of the hives. Is that possible? If it is, is it okay to keep taking the z pack thing without taking the cough syrup?