About 4 years ago I got into smoking natural herbs. I was putting chamomile, colt's foot, and damiana in a glass pipe and smoking it all together. It would make me feel very relaxed and floaty for a bit and then I would fall asleep. Today, my memory is very bad and I seem to have a hard time learning things. I'm wondering if even the few months I smoked those herbs could have done permanent damage to my brain?