Currently i am taking sertraline and hydroxyzine for anxiety and deoxicycline for a skin infection. what is a good cold medicine for a lot of mucus?

Be cautious: You already are on hydroxzine, which is an antihistaminic, many cold medicines would contain an antihistaminic too, combining them would cause CNS depression. Doxycycline, an antibiotic, might not work, as you can very well have a viral upper respiratory problem. Saline nasal wash, and salt water gargles, if sore throat, will help, if no improvement in a day or two, see your doctor,