Sinus drainage? Help!

I am hoping somewhere someone knows how to help me with this. I have had pretty bad sinus drainage since my teens and it sometimes makes me nauseous or even sick. I would sometimes take an allergy medication or a decongestant, but now that i am pregnant that's not an option. Im about 7 weeks so I am nauseous constantly from the sinuses plus the baby. Does anyone know how i can prevent the mucus from draining down the back of my throat or get rid of it completely? Saline sprays make me gag horribly :(