Eye strain, pain in left eye. I consult!

I have -5.50 power of lens in left eye and -5.0 in right eye , I went for a normal eye test at an optical shop today as I am having severe pain and heaviness in my left eye , the power was same , no change yet ,I used to study for 10 hrs a day ,with books ,laptop and phone and can't delay and compromise at all , the problem is after every month or more ,I feel heaviness and pain in left eye , same sufferings now a days , and the shape of both the eyes is different , left one is like contracting and right one is normal in shape and work both , the pupil 's position of left one is slightly displaced But the power of lens is same as it was 2 months ago i.e mentioned above  but I feel my left eye is hell weak ,felt irritated , what to do , And MOST Importantly THAT optical shop owner suggested me to go for DILATE TEST , what is it , should I consult