Just a thought, have you ever  thought to ask if he may be having seizures? My son for years would have the eye blinking, and face scrunching thing going on, we wrote it off as a nervous behavior. However at the age of 15 we found out he had been having seizures for many years. I do not mean to upset you, but it is just a thought.

First of all, the Ritalin my help his attention, but stimulant type medication like Ritalin will actually increase the symptoms of taurettes.  There is not an approved treatment, that I know of, for taurettes syndrome.  I am strongly against Ritalin and other amphetamine based medications, because they are very highly addictive and can cause serious cardiovascular problems. These types of medications have been links to heart attack and stroke.  The dose your son is on is a very low dose, however his body will begin building a tolerence to this medcation and he will then require higher and higher doses.  These amphetamine based medications have also been linked to an increase risk of becoming a Methamphetamine addict later on in life, which is a very sad and horrible addiction-I know because that is exactly what happen to me. I was on Ritalin and later Adderall as a child for ADHD and I ended up as a methamphetamine addict in my teenage years, quitting meth was the most difficult thing I have ever had to do and most of the people who develop that addiction are unable to stop using it.

If your son has ADHD and needs help concentrating in school you should try a medication called Strattera, it is the only non-amphetamine based ADHD medication currently on the market and it has been shown to greatly reduce the symptoms of ADHD.  I would strongly urge you to try something other than Ritalin or Adderall for your son's disorder.  Seriously, Ritalin is like giving him the street drug "speed"(methamphetamine) and no child should be on that intense and addictive of a medication- unless they have already tried everything else and nothing else worked.  Ritalin should never be the 1st drug that is used! Taking that type of medication will inevitably shorten his life span as well, because it increases heart rate so much. The risks in this case may totally outweigh the benefits of this medication!

Have you had his vitamin D checked?  I would do this immediately.  If it is less than 40 ng/ml, read my profile, look at the "tips to take to your doctor" section, and get him to your doctor for immediate treatment.  This could be being caused by a vitamin D deficiency. 

May God Bless You.