Hang in there buddy
This was really bad for me early on - and it still happens. BerryBean is pretty much on top of it. I thought I was seriously dying. And when I didn't drop dead, that only made feel worse. It gets better, and learning a few coping mechanisms helped me.
1. Formal mindfulness-based meditation (google Tara Brach guided mediation).
2. Grounding. I will sit in my chair, feel the contour of the armrest, identify smells, sounds, light patterns - something to identify the moment and the things that are ACTUAL and REAL (not the racing negative thoughts).
3. Distraction through exercise and hobbies.
4. Cognitive Behavioral Therapy (CBT). think about what your mind is telling you with the racing thoughts and evaluate them for reasonableness.
Also, don't be afraid to reach out to a legit counselor to help you through it.