Irregular and nauseous in throat?!

I just stopped birth control a little over a month ago. My first period was horrible!! Now I am about 3 days past my projected next period and it hasn't come.  I have taken 2 tests and both are negative. Now, I know the late period could still be my body getting back to being regulated. However, for 3 days I have had a nauseous feeling in my throat and have almost thrown up.  I am finding it bizarre because my stomach does not hurt and the nausea is only in my throat. Thoughts?!