You probably need to put glasses with a small diopter.
This is the most common case of this kind of eye pain and eye muscle strain.
Tips if you want to delay the appointment to the optometrist:
Blinking more will moisture your eyes better
Yawning will help you to produce more tears
If you use computer, your monitor should be to the side of the window.
Not in front or behind, because this may cause eye damage or glare.
Close your eyes, look at distant objects from time to time. This will help you to relax your eye muscles.
Proper nutrition and exercise may heal everything even if you don’t do anything else.
See a doctor
It’s good someone trained in eye problems to look at you but also do your best to take care of yourself alone.
Ophthalmologist may put you some diagnose but eye problems can’t be cured with a simple pill.
You may also need glasses and an optemetrist may give you an exact prescription for your eyes.