Is it the beginning of labor?

I'm 35 weeks pregnant and I feel so lethargic, nauseous, dizzy, and I have BH( I think, hubby says it could be back contractions). I have been getting really bad hot flashes to the point where I can walk outside in 40 degrees and be sweating. Baby girl is definitely lower. First pregnancy and I don't know what is going on. I've been drinking plenty of water and even Gatorade every once in a while because I know electrolytes and whatnot. But I need some advice. Next appointment is Wednesday. What should I do?