Some hospitals have out of hours emergency hotlines for T1 diabetics. At levels of 22 I would (if it was my scenario) be phoning them - if your sons hospital has this extra service.
As above, but just to confirm really that your son is T1 so he will need whatever insulin is necessary to keep him under 8.0. Please do not fear the fact he is needing insulin..its not a sign of getting worse, you can only think now that you need to give whatever insulin is necessary to keep his bloods in normal range.
Christmas time tends to be needing more insulin for most of us due to the abundance of food that is around. The carbs in food may just go up by say 10% but that 10% needs more insulin.
Never think you have failed.. honestly, think well, ok learnt from that. Next christmas/holiday etc we know this happened so we'll do this instead this christmas.
Heck, we never get everything perfect!! Its just learning and adapting from
now on. No beating self up!!
Contact your DSN and they will advise.... have blood readings and details laid out to go through them etc..