It sounds like premenapause hot flashes. I started in my 30's. It takes years to complete menapause. I stopped had hot flashes in my late 40's but now I am 55 and having them again the same way you are having. It is a hormone imbalance.
i tend to agree with mkh9 it sounds like pre menopause particularly if you have had a few children or started your menstrual cycle early on in life. I am 34 and have just started pre menopause for these reasons.
It could be peri-menopausal symptoms. They can come on around 10 years ahead of when you start menopause. I had drenching night sweats about 10 years before and I am not yet in menopause but I am close. Have you had your FSH taken? You may want to talk to your doctor about that. I did it by taking the FSH the week after your period on a Monday (if you are a Sunday start on the birth control). So you take the blood test on a Monday and take two birth control pills on the Monday instead of taking one on Sunday after you get your blood drawn. Hope this makes sense. This is how my doctor told me to do it. I am still peri-menopausal and now getting hot and cold but no sweating. It could be that believe or not. Alternatively, you could take notes on your diet to see if hot foods (Chili hot) cause this or any other triggers.