What Causes Sudden Loss Of Memory And Disorientation?

3 evenings ago I was helping a friend find something online. Suddenly I could not focus, and had to remove my glasses when I got real disorientated and felt nauseous. This lasted about 5 minutes and gradually I felt well enough to continue and tried to forget about it. Now 2 nights later I am wondering if I should "forget" about it. Should I be concerned?