Hey Alexander,
I’m a 20-year-old male, similar to you, I have been facing chronic illness as well. My main symptoms being a rapid heart rate, fatigue, ligament/ tendon pain, and headaches, I went to many different cardiologists and other doctors, even the ones at the hospital, couldn’t figure out why. I continued to search and both a holistic doctor and naturopathic nutritionist think Lyme/ other infections. I got the standard tests done but they were negative, but I was advised to get a specialized test and it came back positive. I was a little apprehensive to start treatment because the first tests were negative but after doing the herbal treatment I’ve been feeling better, almost no fatigue. I haven’t yet done the antibiotics they want me to do but probably will soon, just being cautious any time medication/ therapist are involved.
So I have seen that Lyme/ co-infections can cause lots of weird stuff even without a known tick bite or rash or fever (like in my case). I would look into it if I were you and even if the standard tests are negative not totally dismiss it as a cause. Not saying you need the expensive special test but just an option.
My cd57 was low and white blood cells were also low pointing to chronic Lyme. You should get a copy of all your labs and check stuff like that, and get a doctor to take a look. ( if they aren’t low for you it doesn’t rule it out, just something to look at)
If sun or sugar bothers you that could be a clue, also maybe if your sensitive to things like chemicals and allergies more than before. Just an idea.
I would keep an open mind on it maybe being Lyme but make sure you had other possibilities tested as well. If you go to a Lyme doctor they will most likely tell you it’s Lyme. When you're a hammer, everything’s a nail. Ha, but really, question everything and meet with a few doctors for different opinions.
Maybe diet could be something to look into, gluten-free, low fodmap (google it, not as well known), or dairy free might help you.
Best of luck and God bless.