I guess I misunderstood. I thought you got the numbers at the vet. Still, if they were taken right after you got home, I would just throw them out and start over. (Vet/travel stress) Give him time to chill and take another test.
NO, you should not give extra insulin during the cycle. That would really throw things off and could be dangerous. Remember it is better to be high for a day than low for a minute. Give the lower dose a change to work, at home with no stress. The higher dose brought him down too low, and then back up too high. If you give the new amount for a couple days and see consistently higher readings than before, then you may get different advice.
Did you talk to the vet about a different insulin?