Could i have Alzheimer's at 21?

Hi, i'm 21 years old, Male. I dont know if that has any relevance? Anyway i was lying in bed... i think i must have been half asleep but i forgot where i was for a second.. it took me a couple of seconds to realise i was at home.. I'm also forgetting peoples names and places.. i've always been good when it came to remembering stuff.. whats wrong with me!? is it stress? am i going crazy? cheers