Answer :
I don't believe dyslexia is a born disorder, and can be developed at any stage of life, given the circumstances leading to the development. It doesn't occur out of the blue, there is always a reason for the development of a learning disorder. I would not jump to the conclusion that you have dyslexia, though. It is simply a possibility. Other reasons your reading and writing could be affected includes lack of sleep, hormone rampages, environmental changes, etc. etc.
Yes, it is possible for you to have dyslexia at any age. Since you're having issues with reading correctly right now, you may possibly be developing dyslexia and you may want to consult a doctor for an exam/test.