I Was Diagnosed With Anxiety & A Phobia, But Can't

I was diagnosed with anxiety & a phobia, but can't remember the exact terms. I have a problem going outside alone and going for a walk ever since I was hit be a truck while walking in a parking lot. I was ejected into the air, landed on the trailer hitch of a parked truck, and ended on the ground facing the sky. Now when I try to go outside to go for a walk, etc. I start to get anxiety attacks and must remain inside unless there is someone else there with me.