Your symptoms remind me a lot of those I was experiencing several years ago, and still do—although to a much milder degree.
I've had nearly every test one can imagine for diagnosing bowel issues; I've also had very little conclusive evidence of any single thing being the cause.
I'll briefly state some of what I've done that works and what it helps, and maybe some of it will resonate with you.
Weight: I lost nearly 30% of my body weight over the course of 2 years. By elimination, I quit eating a lot of foods one by one that were causing me issues similar to you. At one point I had a measured .75% body fat, and rarely every felt good.
Cognition: I had horrible brain fog, couldn't focus, couldn't concentrate, and by the end of the day just wanted to go to sleep to make it all disappear.
Strength: Couldn't really find the will/energy to work out much, lost almost all of my strength. Felt weak, looked weak, and acted so.
Tension/Anxiety: One of the things that really drove me to change my lifestyle were these really intense physical episodes I'd have where my entire body would feel so tense that I thought my bones might crush. I still have NO how to describe them medically—maybe severe magnesium deficiency, calcium, or etc.
Constipation: I'd go 4-7 days at a time without pooping, and When I did it'd be like something from a horror movie.
Misc: I had itching gums at random periods, would get very itchy skin from being in the sun very long, and had some moderate allergy symptoms pretty much always. Also, I didn't realize it at the time, but I wasn't sleeping well AT ALL. It took me getting on a good sleep schedule to finally realize it.
What Helped: I'm going to condense this a lot; But feel free to ask me about anything in particular and I can elaborate. I'm a writer for the Organic Newsroom, so you'll have to forgive me if some of my references are to that site; but I'm very familiar with the content there and trust it entirely.
Proteolytic Enzymes: These are like digestive enzymes, but you take them on an empty stomach between meals. These help so many things it's hard to narrow down, like lymph cleansing, protein cleansing,
parasite cleansing, etc.. By far, the best one's I've tried are Doctor's Best Proteolytic Enzymes. You can get them on Amazon for like $16 a bottle now.
GABA: GABA has been amazing for me. It seems to jump start my hormones in the morning, helps me poop a little, and really helps me sleep soundly. I take it first thing in the morning on an empty stomach, and also like 3-4 hours before bed on an empty stomach. Warning; sometimes it has this really weird side effect for me in the am where I get really tingly sensations, and shortness of breath for like 30 seconds. First time scared me; now it's just kinda fun :)
reference: organicnewsroom (dot) com (slash) gaba-supplement
Anti-
parasite Herbs: I've tested positive for several parasites, and have honestly forgotten several of them. The last one was round worms, which was about 6 months ago. One prescription medication that helped was called Ivermectin, but Rx scares me. I was able to see many of the same types of benefits from herbals though; particularly one called 'Intestinal Tract Defense from Herb Pharm' and one called 'La Turista'. The second is really hard to find anywhere, and the first is usually only online. A lot of local health food stores carry Herb Pharm though, so you can check there. Whole Foods carries them as well. I've resigned to the belief that everyone should be taking these types of herbs on a monthly basis, around every full moon, for 3-5 days.
reference: organicnewsroom (dot) com (slash) parasite-cleanse-review-guide
I've noticed personally that my symptoms come in cycles, which I have realized now are pretty in line with Lunar cycles. When my doctor first told me that
parasites activity is highest at the full moon, and lowest at the new moon; I thought she was batshit crazy. However, it's definitely got some credibility in my mind.
I work out, hard, at least 4 days a week. I stay active, stand instead of sit, and run around a lot randomly (I hate actual running). This helps me keep my energy levels up, which seem to help everything else.
Ultimately, I found that treating my issues as systemic instead of one particular thing has offered me the most benefit. I would also testify to the power of finding the guidance of a good integrative doctor. I bounced around a lot until I found one, and then I really seemed to catch some traction. I feel the best I've ever felt in my life now, and feel that month-by-month, I'm still improving. I cook all my own food as well, and only eat Organic and Non-GMO. However, if I slip in some non-organic stuff I don't notice any immediate shifts. Trust that your body has the tools to heal itself, and consider how you can best revitalize those tools.