I'm now 49. I think I'm going thru menopause. I've been getting the hot flashes for a couple of weeks now. About a week ago, I started having slight pain more like discomfort between my armpit and left breast. I first noticed it at work while leaning over and trying to take a breath. Then gradually it went from chest area to the armpit/left breast area which is now tender, no lumps or bumps just slight pain. Also, I have slight pain when trying to stand or sit up from a laying down position. What could be causing that ?