Welcome to Lantus Land.
I don't mean to be dense, but I'm not sure I understand how you've laid out the numbers on your spreadsheet. It looks like you've got 2 rows per day. If that's the case, it also looks like you've got 2 AMPS values and a PMPS. I'm confused. If you don't mind, could you walk me through how you've arranged the data?
If you think a vet visit is in order, I'd trust your gut. FWIW, my cat went through several bouts of diarrhea. After getting her tested for just about everything including parasites, we tried a course of metronidazole for a month. The shorter trials seemed to help but the diarrhea would return after several weeks. Since the longer course, it's not been a problem.
Winkley's numbers actually look good. What I woud suggest is that you get some spot checks. Since Lantus dosing is based on the nadir, if you're giving insulin, you'll want to make sure that he's not dropping unduly low mid-cycle.