Have had hot flashes since my mid 20's. Face/ears flushed. Have been taking birth control (zovia 1/35e). Why hot flashes so young?

Get tested. There are several possible reasons for hot flashes, and you need to get tested in order to find out if any of them pertain to you. Some can have medical implications, such as with thyroid problems, while others can have fertility repercussions, such as in premature ovarian failure. See a reproductive endocrinologist and get tested!
BC pill. The bc pill works because it interferes with the period cycle controlled by the lower part of the brain. The hot flashes are due to irregular controls of ciculation through the actions of the autonomic (automatic) nervous system. Remedy: stop using pill. If it is now for birth control, find antother method.