Nauseated since 1 week. Wrong with me?

I often have problems of constipation due to which i suffer from gastritis, but it is only for a day or so that too once or twice in a month not more. Right now I'm feeling nauseated, I'm having burps again and again since 1 week in the mornings which usually dissolved by evenings. I'm not even having constipation and even after taking pantoprozole i don't get much relief(relief lasts for only 1 or 2 hours). I have a history of PCOS.  I had unprotected intercourse 2 months back and another 5 months back, took an ipill (both times) had withdrawal bleeding from ipill - both times but this time, 2 months back only for 2 days. Also did urine pregnancy test, both times, which was negative. Also i had cough from past 5 days (dry cough at first but normal sputum since 2 days), having lecuf and Amoxicillin for it. Why i am having nausea? Is it related to pregnancy or what is wrong with me?