Very sorry to hear what you’re going through OP. I truly hope you find a solution.
Have you taken a look at your diet? I mean literally have you taken a thorough diary of every single thing that passes your lips over a few weeks and taken notes of how you feel afterwards? I recommend you do this and keep a thorough diary.
I could be completely wrong but if you have not investigated your diet and changed it, it’s something you cannot rule out. Think about it, you put food in your body constantly every single day of your life, so it could make sense that something you are eating is causing these odd reactions in your body.
You could have developed adult onset allergies. This happened to my wife a few few years ago and she was suddenly allergic to various foods that she has never been allergic to before.
She experienced many symptoms that you describe but not all of them. It took about a year and a half before we realised her symptoms were caused by food. Doctors were useless. She had every test with the doctor just like you and everything came back normal. She had cameras up the bum, cameras down the throat, biopsies, blood tests, the lot and nothing concluded anything was wrong and according to the doctor she was in good health.
I eventually started by saying she should cut out gluten from her diet and she immediately saw an improvement. She cut it out of her diet for a few weeks and now, any time she has the slightest bit of gluten and she has an extremely noticeable and tangible reaction. Different foods cause completely different symptoms. Not all gluten reacts the same. We have gone on to learn that she’s allergic to quite a number of foods that she has always eaten all of her life. Some of the foods that she is allergic to are not one of the recorded known allergens. It’s just like one day she woke up and the body decided it doesn’t like those foods.
we’ve all heard the phrase you are what you eat but food is the most stealthy of things that can harm you as most of the time we are not thinking about what we are eating.
Obviously I have no idea what your diet is like, but a good starting place is to eat food that is fresh and non-processed and that has been grown naturally in the Sun, think paleo diet, with the exception of anything wheaty or gluteny. So back to the basics of fresh fruit fresh vegetables lean meats nothing processed, beans pulses. Possibly even avoid or test out lactose. You may want to do a process of elimination first and anything that is a registered allergen would be a good start. If you do a diary of all of your food for a few weeks you will see patterns and you might be able to draw a conclusion.
We have done lots of research for the past few years and I’ve read many stories of adult onset allergies, and sometimes it doesn’t make any sense as to why this has happened. Look it up yourself. Apologies if this is wrong but certainly something to consider investigating at the very least, given your situation.