Can you see a doctor? the doc may send you to a psychiatrist or neurologist but they could assess you. Your age gives me lots of hope that you can recover with guidance from a doctor. A doctor may find nothing wrong but then at least you can stop the worrying because that will also affect your health. I have a severe brain injury, severe brain stem injury, severe head injury and a skull fracture from a car accident.
The brain injured don't usually have trouble sleeping, we have serious arousal issues. Hard to get my brain to wake up and get the connections going. I was abusing coffee and energy drinks until a doctor Dx me with post-traumatic ADHD (caused by the traumatic brain injury) and put on meds that would make a normal person climb the walls but they just wake up my brain and I function much better.
See if you can talk to an MD or nurse practitioner about your concerns.