What Causes High Blood Pressure During Breast Feeding?

I am breastfeeding and have high blood pressure. I am taking 200 mg labetalol twice a day and my blood pressure is currently pretty steady around 105/65. I have a cold and the congestion is making it to where I cannot sleep at all. I know cold medicines are a concern for both breastfeeding and hypertension. But if I don't get any sleep, I'm going to go crazy. Can I take Coricidin HBP Cough & Cold? My mom has hypertension and says this works for her.