Gunni

Hey Talia4, I still try to stay on the lower end of carb intake but things are way easier for me these days.
It really looks like a digestive issue at the core in my case
 
As supplements with meals I'm now taking
3-4x 650mg betaine hcl without pepsin (to handle larger doses)
1-2x Doctor's Best digestive enzymes
 
And daily Share Pommelozzini.
This has helped my digestion immensely with carbs and fats. I'm way more tolerant of larger meals and things are a lot easier. Happy to hear any progress or findings on your end as well though!
 

30 grams of fiber seems to be the magic number for me insofar as regularity goes. And make sure you drink plenty of fluids with it if you take psyllium.

Another thing that is often mentioned here, magnesium citrate is a supplement that many celiacs need to take, and it can act as a laxative as well. You can get a gluten-free version of it at Costco.

Others have definitely reported various changes like constipation after going gluten-free. You might try eating prunes to see if that helps. 
Casein/cow's milk intolerance is very common in those who are diagnosed with celiac disease, as their villi get damaged so they cannot properly digest the milk protein.

The usual place to start is to look closely at your diet to be sure that it, including medications, toothpaste, lotions, etc., are 100% gluten-free. The arthritic symptoms you described are often linked to those with undiagnosed celiac disease, or those with poorly controlled celiac disease. 
Assuming your diet is in order and you're not getting any gluten in it, this article covers some additional things to consider:
 Also, I spend a lot of time on computers and due to carpel tunnel issues switched many years ago to a thumb trackball mouse, which helped resolved many pain issues caused by using a standard mouse:
https://www.amazon.com/dp/B07MVLYT7Z/ref=twister_B07MVPXR7G?_encoding=UTF8&psc=1