My friend uses crystal meth and states that he has been using for 5 years. I have known him for the past year and half, and he has invariably become ill on several occasions in some form or fashion--being tired, general malaise , sniffles, etc, when I (I have never used any sort of drug) might have a cold once a year. He smokes the drug. He reported two days ago he did not have feeling in his feet and hands. Just today, he states that one of his legs seems to be swollen, and he is having trouble walking on it. What could this be?