Nausea, upset stomach, and film on tongue

[Oliver051984]

Hi people. I would like your opinion. I have being having nausea, upset stomach, bad taste and smell, and fatigue for almost a year now. It is worse during the evening. I had sinus surgery 5 weeks ago followed by two weeks of antibiotics. Symptoms are the same now. I have postnasal drip due to my sinusitis ans a yellow film on my tongue. I was wondering if it may be acid reflux? Or could postnasal drip cause nausea and upset stomach? Thanks for your time