My left eyeball feels like it's being pulled from behind on my temporal side. This occurs when I remove my glasses to focus on reading my book. I use spectacles because of myopia with power of -4 and -3 on left and right eye respectively. At this power I have used it for say 3 months. I have been using spects when I was 18. Now I am 22 years old.

It sounds like you may be experiencing eye strain or discomfort related to your myopia, especially when switching focus between near and distant objects. This can happen if the eyes are overcompensating when you remove your glasses. It might help to adjust your reading habits, take regular breaks, and ensure your prescription is up to date. If the discomfort persists, a visit to your optometrist would be a good idea for a thorough check-up.