What can we do?

So ever since this girl slipped something in my boyfriends' coffee he's been able to get up but not able to stay up. He also gets really really tired after and we haven't been able to have sex ever since. It's really making him depressed and I'm really concerned there's something really wrong. He went to the doctors and they ran blood tests and said he's fine but it's been almost 3 months and he still hasn't gotten better. Anyone know what could possibly be going on or what to do?