I had a bad sinus infection a couple months ago- and instead of being able to blow it outta my nose, it was going down my throat & i never even knew, til i went to the doc b/c i had a bad headache (like a sinus inf.) & he looked in my throat and was like "EWW!!" lol.. i didnt know what it was.. but he told me it was the post nasal drip... While it never made me nauseas at all, it is definitely best to 'hawk' it out every few min..like as often as u can..so u can spit it out instead of swallowing it. Then u have nothing to worry about. Asl u could try a nasal spray or some kind of decongestant (or inhale some steam..) and that will clear your sinuses more where u can blow your nose if need to. But as long as u can spit tht stuff out, it wont go to your belly..and u wont have to worry about it making u n*