Sounds like your student is over-thinking and as such task saturated. I'd have him fly with another seasoned flight instructor. Then I would suggest your student spends about 5 hours in an ATD like Redbird with a good sim instructor. See if the student starts to settle down now that he's not flying a real airplane. If your student is still showing no progress, then sit him down, give him an honest assessment and tell him you can't keep taking his money and that he should consider another career. Maybe you can suggest he start flying RC airplanes which may help him figure everything out. One of my sharpest students came to me with over 5 years of RC experience and I solo'd him in 5.5 hours.