Doxie belly trouble

This applies to both of my dachshunds. (Mini 4yo male & 5yo male)

It happens randomly.

Happens only at night around 4-5 am.

So what happens is one will wake me up by whining or shaking. I hear belly noises (a wet, wispy sound). I take them out- they immediately look for a specific plant (I haven’t been able to identify yet). They eat a bunch of it, pee, and we go back to bed. The rest of the night is fine.

I thought maybe they were starving so I split their two meals at 9 & 4 to 3 meals at 9 & 2 & 6. Didn’t make a difference.

They have had homemade food for years. I use a variety of recipes including a wide variety of foods. Thought maybe it was that so I did farmers dog food a few months but no difference.

I don’t know what it could be, but it bothers them and messes with our sleep. Any ideas?