I can't focus on one thing at a time.must multitask. can't pay attention in class. my mind just wanders, i can't control it.even been forgetting things?

Attention Disorder: You may have attention deficit disorder. You should see a psychiatrist or psychologist for a full evaluation. If you don't pay attention to something, it can be difficult to remember.

In addition ...: Your symptoms could result from adhd (as already noted), and they could also result from stress, anxiety, side effects of medications, drug use (mj), mood disorders, thought disorders, learning disorders, and several medical conditions. Have you had a thorough physical by your primary care doc? If so, an eval by a mental health professional is recommended.