Anxiety killing me

So I've been having this problem for awhile. Back in high school when I usually have the presentation to present I could never do it I always have this feeling in side like am gonna get get an panic attack or something...even now it still happens so I tend to stay away from crowd this is one of the reason I don't have a job. When those stuff cross my mind I feel like am gonna i don't know how to explain the feeling.... Now I'm getting a job and am kinda feeling that way but also excited to be making my own money..I don't know what to do or how to overcome this feeling like my heart keeps beating and stuff