Can you let us know if you shot or not? Have you fed him and if you have, how much and when? If you haven't....please don't until you read through here and we make a plan.
Do you have plenty of test strips, HC food/gravy, karo, and can you be there to test him..are you rested?
Usually when you get a low number that you haven't shot before, you have three options.
1. you can stall and test every 20 mins and see if the number rises; as soon as it rises, shoot his full dose (I believe it is .5u?). If you stall, you will shoot tomorrow 12 hours from this shot...we make up time in small increments which i can tell you about later but you will need to be able to shoot later tomorrow
2. shoot a reduced dose on time
3. skip
I'm going to look a little harder at his SS while you read this. Be right back to help you decide, ok?