Lantus is a long lasting, depot type insulin. One shot given will last longer than 12 hours, up to 14-18. That means there is overlap with one shot in one 12 hour cycle affecting the numbers into the next 12 hour cycle. That is why you do not want to give a different amount AM and PM. You want the consistency over time.
The scruff does not have as many blood vessels so the absorption of the insulin can be slower or even more erratic. That is why we do not recommend shooting in the scruff. On the other hand, there are plenty of members here that for whatever reason, have only shot in the scruff area.
You got a BG of 47 last night. That is an automatic decrease using the TR protocol. The decrease should be 0.25 units so dose should be 2.75U.
With that low number last night, Shadow will be bouncing into higher numbers for about 3 days. You need to hold that decreased dose for at least 6 cycles, maybe a bit more until he clears the bounce and has time to settle into the new dose.
ETA: Definitely NOT time to increase the dose. When you make dose changes, you only want to change in 0.25U increments. After that hypo last night, and the scrambling you did to keep his numbers up, now you see why we wanted that before bed test. I bet he dropped even lower the night before which is why you were seeing those 400+ numbers on Sunday.