Hi. There could be a lot of reasons behind not being able to concentrate. It is natural for you to feel scared but it is great that you are acknowledging these symptoms and looking for solutions.
I would suggest you to see a psychologist/counselor and they would help you figure out the reason behind the existing problem; further giving you tools and techniques to overcome the same.
Next Steps
See a psychologist/therapist. These are symptoms which shouldn't be ignored and are not something that can not be worked on. My organisation and I would be happy to help.
Health Tips
Don't just brush it off as something trivial and not do anything about it. It is okay to ask for help and solve it before it becomes too much to deal with. Good Luck !