Can allergies to pets cause brain damage?

I'm extremely worried that I may have sustained brain damage. My reason being, is when I do my work, I seem to see that I've missed certain things in my work. My lecturer isn't much of a help when I ask him such things as "Have I missed anything in my report?" to which his reply was "You're just asking for answers"

On occasion, I get some pains in my scalp, nothing too unbearable. They're very mild and do not interfere with my day-to-day life. What does bother me is the immense headache I get from playing minecraft, when I concentrate (I was trying to create a skull out of cobblestone) I got an extremely bad headache, it was extremely unpleasant. This also happens when I draw, although it isn't as bad as when I'm playing minecraft.

Also, sometimes I get confused when reading some simple sentences and often repeat them over and over in my head until I understand it.

Have you ever been tested for dyslexia? It is even possible for some allergies to aggravate it, but it normally goes away when the allergen is removed.