A little help please!

This is probably going to be a long post, but I feel like the community should know the context of what's going on to help with giving advice. Advise I sorely need right now.

My father (84YO) has had type 2 diabetes for over 40 years and has always had/kept it in check without to many problems. I guess a great thing about him, is that he actually listens to his doctors and follows directions to the letter.

However, about 6 months ago he ended up getting DKA and was hospitalized for about 5 days. Every since that point we have struggled to keep his BG in check. Everything we thought we knew about his BG seems to have changed overnight since that point.

We started him on the Omnipod Dash after has bout with DKA, and I admit that it has helped tremendously in the management of his diabetes. However, there are things happening that make no since to me, and when I bring them up to the doctor, their answer is usually that he is old.

The following are the patterns his diabetes follows:

From 7:00AM to around 12:00PM it is usually on the rise. However, with an increased basal insulin setting we can normally keep this in check.

From 12:00PM to 2:00PM it seems to be controllable as well.

The issues start around 4:00PM. Everything seems to change at this point. His BG levels start dropping quickly. For instance, if we fed him the exact same meal that he ate at lunch which raised his BG by 40 points, will only raise his BG 10 points at the maximum.

And the largest issue he has starts at this point as well. If he walks even 30 feet to go to the restroom, his BG will drop sometimes up to 50 points. If he decided to take a shower, it would drop up to 100 points. These readings do not "bounce back" they just stay low.

I have had to micromanage his BG to have him around a reading of 180 before he goes to bed, because he will lose 80 of those points just walking to the bedroom. Then it will continue to drop, falling right past 70 unless we give him Glucose tablets and about 4 ounces of orange juice, which will bounce it back up. The rest of the night after that is relatively ok or at least manageable.

It can't be healthy to use Glucose Tablets every single night can it?
Is there something I am missing or not having him do that is making this happen?

Also, we have lowered the basal settings significantly after 4:00PM so I don't think that is the issue.

I think this huge post boils down to, why does walking 30ft cause his BG to drop 60 or more points?