My Son Age 20 Has Been Taking Vyvance For A

My son age 20 has been taking Vyvance for a month and he was doing very well. He ran out about 5 days ago and sub stunted Aderall for a couple days. He started to act very strange. Could not stay on one topic. Forgot things like where his phone was and did not care. He went to the hospital and the ran lots of test even a spinal tap. He did not have any drugs in his system but the Adderall and a little bit of weed. He is still not acting like himself three days latter. Still can't stay focuses. Rambles on and goes from one topic to the next. Should we get him back on the Vyvance that he did so well on or nothing. Please advise