do I have a yeast infection and what should I do?? is this normal?

I think I have a vaginal yeast infection. I've been nausea and have had a headache no matter what I do. I feel like shit and am tired. I hace chunky discharge and it's whitish and sore. I haven't had sex in about 3 weeks and went to the gyno cleared out almost 2 weeks ago. I'm wondering what caused this and what should I do??? I might get the store bought test and go from there. does cranberry juice really help?