Tiger is driving me crazy again..

Had a perfect day yesterday, low hundreds all day. Had to wait an extra hour to give his pm shot because he was low. Today; totally different! He started high, went very slowly lower, and instead of going back up, he is still dropping! I've fed him supper, which I know will raise his numbers, but I don't understand why he drops like that, instead of curving. I can't stick on a dose when he varies so much. I want to bring him back to his 9/9 times, but now we are at 11pm, and I have to test him again to see if I should shoot. Argh!!!!!!