military briefings

I am in the military, a life that deals with briefings day after day. When I was younger, I did not have a fear of speaking in front of larger crowds. Now I'm 45, still in the military and for some reason as soon as I know I have to speak my heart starts racing and my voice always trembles. A hypnotist in California said if a person has had surgery, sometimes it can trigger a fear of public speaking so I thought maybe that was the problem. I would like to get rid of this fear as it could hold me back from future promotions.