"I have bowel issues, my legs/arms can sometimes feel heavy/odd, and sometimes I have pain [more like soreness] in my lower back/hips when I've eaten but am constipated." You literally have the exact same problems I'm struggling with that no one can find an explanation for. About 2 years ago I had troubles with gagging all the time and they diagnosed a small hiatal hernia, for that I took PPIs then about a year ago in May 2019 I noticed a sudden change in stool it took on every form or colour imaginable and I had a lot of pain in my epigastric area. I did multiple blood tests which only showed elevated levels of bilirubin but still within non dangerous levels. I did CT scan of abdomen and thorax which were both normal. But yea for a year now I am super fatigued all the time, my legs and upper arms can feel really strange (like a mix of crawling, heaviness, weakness, creepy) and I also feel weird/sore around my kidneys in the back but I can also feel it on 2 points from the front of my body (where my kidneys would be located).

I do not think Restless legs was the correct diagnosis unfortunately. Your case seems so similar to mine and I believe it is something in the gut. Just yesterday by chance I discovered that after oversaturating myself with vitamin C, which leads to watery diarrhea made me feel temporarily a lot better. I'm theorizing that there could be a bacteria or fungus in my gut that releases toxins that produce these symptoms in me. And the watery diarrhea acted as a kind of gut cleanse for a few hours which washed away the toxins for a period of a few hours.

You could try the experiment yourself if you have symptoms, if you experience the same relief it could point us both in the right direction. I drank half a glass of water mixed with a teaspoon of ascorbic soda every half hour until I have to rush to the toilet (Your guts will rumble a lot). It usually takes like 4 glasses and you'll end up an hour on the toilet.

I have also had internal tremors for almost 4 years now. Along my journey of trying to figure out why, I have been diagnosed with small fiber neuropathy by a neurologist and gastritis from an upper GI I had done. I also have seen a naturopath who drew a lot of blood. (much more than a regular doctor). Some of my B vitamins came back low or low normal (B12, B1, B2, B9 in particular). My vitamin C was almost non-existent! I also did a breath test that came back positive for SIBO which also correlates with the gastritis and chronic constipation I was having. We have come to a conclusion my gut is not working well due to SIBO and I'm not absorbing my nutrients. SFN can be caused by B12 deficiencies. I also have the MTHFR gene variant which causes me not to absorb regular synthetic B supplements that many foods are fortified with so I have to be on the Methyl B vitamins. I am starting on small doses of them as I am finding larger doses causes my SFN to worsen. I also did a course of herbs to kill the SIBO. I had recently read a thread of someone that internal tremors who took a B complex vitamin and it went away. I am hoping that with supplementation it will eventually go away. I have read it can take months though. If you want to have any labs drawn on your own you can go to requestatest.com and order any labs you want.

Any thoughts on whether or not the internal tremors could be perimenopause?... hormone levels?
I'm dealing with them too.
Started with one episode in December of 2021. .. then another in January of 2022. Than an eye twitch in April of 2022. Some random shaky vision episodes ( which I still get) and now I'm have shivering, shaking and internal tremors often. Worse episodes at night. Very scary.
I have also developed anxiety that started in August 2022.
I'm a 52 yr old female... being treated for anxiety and HRT hormone replacement therapy only at this point.
My labs are also good.