At your age, you do not have to worry about memory problems. In fact, what you feel as memory problem is actually decreased concentration due to which you are not able to focus properly when you read. This can be because of many reasons like stress
, lack of interest or distractions.
Here are some things you can do:
1. Set short term and long term goals, so that you know why exactly it is important for your to study. This will increase your motivation and also your interest in studies.
2. Study with full concentration (without distractions), even if it is only for a short period (1 hour). Reading for hours without focus does not help you in long run.
3. Take breaks in between so that your mind does not drift away while studying. You can utilize the break to relax and refocus.
4. "All work and no play makes Jack a dull boy". Integrate some play or exercise in your routine. Deep breathing exercises will also help calm your nerves.
5. Do not compromise on sleep time as sleeping less will affect your concentration.
If you can follow these (all self help methods and costs only your time), then it may not be necessary to even consult a doctor. All the best.