The weight loss is probably why you dropped where you might have stayed level.
As you lose more, your resistance will drop, especially if you're exercising too. You can ask about splitting lantus, if your DSN has experience of it.
There's a couple of us doing it successfully, so it can be done. If your DSN doesn't like it, you can swap to levemir and split that.
Rather than DP, it may be either lantus runnign out early (if you inject in the morning) or if you eat late or have a betime snack, it may hang over to the morning.
Rob