I wouldn't bother with testing anything.
Do a whole30 and you will know exactly.
When I first started, I went in slowly and reluctantly. I thought a whole30 was a bit extreme. Now I live that way most every day.
For me, it was the symptoms I didn't know I had.
I was like - woah, I haven't noticed XXX in a while.
and there were like 6 of them for me.

Hi there

Very similar thing for me. Turns out I am intolerant of all grains, eggs, almonds, brazils, soy and have a dairy allergy. The grains caused me excrutiating stomach pains. Plus there is also fructose malabsorption, so high fructose fruit makes me kind of "drunk" and have gassy. But fruits and veggies with a lot of cellulose give me digestive distress (no drunkeness to sweeten the pill even). Then there was the yeast overgrowth- it died off last week and that wasn't too pleasant for a few times.

So there is the pity party over, but do want to know the good news? Each time I found something causing me a problem and I cut it out, a different symptom went and often I lost a bunch of weight, with no effort (other than cutting out the item) real fast.

Cut grains: Lost five pounds in a week- the worst of the stomach pains went
Cut dairy: Lost the sinus trouble
Cut high fructose fruit: Lost 7 pounds in under a week- couple of pounds a day sometimes. Bloating lessened significantly and my stomach just suddenly flattened
Cut high cellulose vegetables: Stopped having to RUN to the bathroom and the remaining bloating lessened
Cut starchy vegetables to help kill off the yeast- lost four pounds in two days and the last of the bloating went. And some weight started coming off my tummy and upper torso.

I figured I needed to give my tummy sometime to heal, so I am following the paleo autoimmune protocol- no nightshades, nuts or fruits. I feel unbelievably better. It took me a over a year of huge struggle and torture to lose the first 14 pounds and now I have lost 25 pounds in a few months with much less effort and increased health.

My husband gave up grains, dairy and eggs and went paleo too. He went from being in pretty good to great shape in about 10 days- from 32 to 30 inch waist and from about 14% bodyfat to about 10%. Whilst eating huge steaks, bacon, pints of seafood, mountains of sweet potato mash. He was sceptical when I first made the shift to paleo and now he loves it.

I really don't think gluten is good for anyone. At all, ever.

Its definitely worth a try to see if it helps your digestive issues. I started eating Paleo 10 months ago when they diagnosed me with Celiac, and it made a huge difference. Joint pain, diarrhea got better, mind fog, dizziness, fatigue....but things still weren't great. There were still issues. I was diagnosed with Crohn's just over a month ago, while in the hospital in major amounts of pain. I'm pretty sure that this major flare was caused because I tried to add rice back into my diet. Way too much of a coincidence otherwise. Add rice back in for a few days, and the pain started within days.

Anyway - Paleo can make a huge difference on how your digestive system works. Even if you do it for a month (maybe try a Whole30?) and then try adding foods back in, you'll have a better idea of what bothers you and what doesn't.