Does anybody know what could cause my vision problems/how they could have started? There are slight vision problems in my family (Both Biological Grandmothers and my Mother all have vision problems. Not my Mother so much as my Grandmothers, though.) It could be hereditary, but I wanted to run it by someone before I get it checked out further. 

Sometimes, after I've been reading, drawing or on the computer for awhile, my eyes start to feel very odd. They go out of focus for a few seconds, come back into focus and feel like they're being constricted (For lack of a better description.). It happens more often when I'm tired, but It also happens when I've just woken up and somewhat randoml throughout the day. I've tried reading some posters from a distance when my eyes aren't out of focus and feel fine, but it is sometimes hard to see then.

Also, I'm very prone to Tension Headaches and Migraines. Both, again, are hereditary.

Any help is, haha, helpful.

Summarized question: What causes vision problems?