Suggest Treatment For Cough And Sleeplessness?

I am being treated for Strep throat. I am taking 875mg Amoxicillin and was prescribed Hydrocodone for my cough. The minute I lay down I go into a coughing fit, very wet and cannot sleep. My first thought is this is drainage and I need a antihistamine but I am afraid I have so much on board already do I really need more? Please help.. Can t sleep