Type 1 Very Weird Lantus!

So long story short, I was on 19 units of Lantus and did basal testing and I was fine. Now I am on 8-10 (still need to figure this one out) and 10 seems perfect when I do basal testing except it drops me throughout the night but during the day nah. Explain this?

Update: someone mentioned that if Lantus has been exposed to heat it works as fast acting. Maybe this is my case so tonight I opened a new pen. I will see what happens