acid reflux, n*, hunger or period

I have been very anxious and n* these past few days. TU* a month ago, and struggling to remember how it felt. I also got my period yesterday. I have a strange feeling under my ribs, but can't decide if it is n* or not. Have barely eaten all day (had breakfast and a banana). Also getting a slightly sour taste in my mouth, but that might be from the coke I'm drinking. I am shaking, which usually means it is anxiety (did not shake when I was sick). I am also a bit gassy. How do I differentiate n* and feeling like i might tu* from the other feelings?

And how can I calm myself down? Have taken some gaviscon, but it is not helping all that much. I do have Nexium (Esomeprazole) as well, but I am a bit scared to take it because of the side effect. Have taken something similar before, and was fine.