Do you have someone you can talk to that you can trust? Many times our fears can be neutralized if we don't keep them to ourselves.
There are a lot of different possible causes. Extreme stress for an extended period of time can dot it. Growing up in a home with active addiction, whether drugs or alcohol, gambling, pornography. These environments can produce severe anxiety. This was the root of mine, my dad was an alcoholic. I found relief in Al-Anon. This is a spiritual program that has helped thousands of people
I don't know how long you've been experiencing this, but if it's been long, another avenue is to find a good therapist, who will listen.
Hope you find this helpful. Don' be too hard on yourself. I will be praying for you.