I understand wat your going thru- I have the same problem. Although it is embarrassing, I was told there is not much I could do.. In my experience, the more times I exercise, the less obvious it is, and after going through so much trying to exercise at times when ppl wouldnt see me- like night and early morning- I discovered certain breathing techniques which, at the end of my run, would leave my face less flushed.
Anyhow I hope you dont let it get to you and watever you do- dont let it get in the way of your exercise!!! Xoxo