My 16 year old son (149 lbs, lost 14 in past 2 months durring mono. 5'8'',healthy otherwise) has developed an involuntary movement of his lower back, it looks like a spasm, but happens every 20 to 35 seconds and sometimes sooner. He also has them during sleep but only like 5 every half hour. He is recovering from mononucleosis which lasted for about 2 months and is still weak and tired. Our family Dr. says its anxiety, and prescribed clonazepam(2.5mg) and cipralex(5mg) as well as voltaren, but its been a week since he started treatment and still no improvement. This has been going on for about 15 days. I would really appreciate your opinion in what this could be and how to treat it if this treatment fails. Thank you in advance.