As B. said, look in your private messages box, located near the top on the left hand side of every page and you will find my mail. Read it carefully and try to take it all in. Ask me any questions you have.
In the meantime, if you really want to start one of the CRABs, Avonex or Betaferon I would say are the ones to go for. John gave you one very good reason above, for kids of any age!
Also I was chicken about the jabs and chose the shorter needle subcutaneous rather the intermuscular!
Only consider this if you insurance covers it, because they are very expensive. You don't want to bankrupt yourself unnecessarily and they only modify the disease by reducing the number of relapses.
Apart from that, diet is very important for everyone, not just people with MS, and Melody can talk endlessly about diet and supplements. In the other thread you started in this forum she mentions Vit D and omega 3 fish oil as being critical. She is right. Fish oil for ADHD as well as MS, so you are killing two birds with one stone here.
Try not to get too worked up about all this, your son will sense it and act accordingly. Think about everything said here and in Melody's postings and my Private Message.