The quickest start towards an answer would be to check your body via blood work and a CT. You might check for CFS (Chronic Fatigue Syndrome). You are exhibiting similarities to my nephew who was 15 when he was hit with CFS. Due to my MS, his mother took him to an MS Specialist who quickly pointed him towards a specialist who handled CFS patients.
If your CT and your blood work are normal, then you might ask to see a neurologist. There are other boards on this same site which might be a better fit for you. Should a neurologist be your next move, you found us and I am sure you will find warm support during your neurology visits.