Anxiety??

I've never experienced anxiety before, up until about a year ago. I used to be fun and adventurous, always out and about, meeting new people, working new jobs, not afraid! Now, I can't even go grocery shopping with out freaking out. I'm so nervous all the time I feel like I'm afraid of my own shadow. I had a new job opportunity and I had to text the lady and tell her I can't because of this. I thought I would be ok but thinking about it all weekend is enough and I havent even gone yet. how do i deal?? I really needed this... I hope she understands.