A medical question about dementia?

I have a problem and I don't know who to ask. I am 21 years old and I am an undergrad student in a university in Egypt. I am not sure, but I feel like I am suffering from some sort of dementia or something. What makes me suggest that is that I feel I have memory loss, I constantly forget the courses' contents once I finish them and I even forget any type of general knowledge info that I read or come across, as if I never knew about them at all. The worst happened recently when I suddenly found out that I am even forgetting how to write english essays. I have to mention that I used to write stories and that wasn't too long ago, maybe last thing I wrote was only 6 months ago. Now and all of a sudden I just can't write or find the words as if I am back to nursery stage or something in English, though I have been studying english for 15 years. I even go back and read my writings in total amazment as if I borrowed them from a friend. I couldn't find anyone to ask him about this matter, so can anyone help me with it? I am living the worst days of my life now because of this...can it be that I am having dementia at this age?