Hormones or an imbalance in your intestines can cause this.
SO a strong Pro-biotic can help. I am not big nor can afford Yogert everyday so this helps me from having as many. Unfortunately our Society and diets can easily throw us off balance and with Fibro then we have issues processing our foods to the capacity we are supposed to. Sometimes we need an extra boost for Balance.
Also Menopause can start having symptoms as early as 27 which include Hot flashes.
Also VERY common to have issues with Liver and or Thyroids. Which means if our liver isn't functioning properly then our thyriods will fluctuate too which causes Hormonal symptoms including dry skin or Hot and Cold flashes. Coconut oil is good start to helping these work better. You can cook with it put it on your skin or even buy the capsules. Milk Thistle is great for helping Liver function too.

I recommend Pro-biotic to everyone and Coconut oil. The Milk thistle or any Liver cleanse thing only if you have a high liver count in your blood work or a family history of liver issues unless the other 2 things don't work then start small until you get relief. A 4th thing is if it is hormonal there are vitamins like Estro-Vitamins that will might help if your hormones are low.

Really This has helped me a TON and I am ONLY 34.

I am constantly putting on warmth then stripping it off. ALL DAY LONG and into the night. On off on off on off. Drives me crazy. Especially at bedtime.

Yes, it's a constant battle with my husband! It can be 40 degrees out and I will suddenly be so hot it almost makes me sick!

Yes!

24 hours a day! No in between; I'm either cold or hot.