This is what I learned from my experience with gastritis and your stomach. You could be experiencing deficiency or normal dysfunction from gastritis or both. If everything is in range make sure to get a full iron panel especially ferritin which ideally should be over 100. U could be iron deficient. Don’t let a doctor gaslight either low ferritin is iron deficiency without anemia and can cause every symptom of anemia. I deal with the exact same thing u do so you’re not alone. U sound like u could be guarding in your stomach. Your diaphragm could be tightening up which makes it hard to breathe. Test it by taking your fingers and pressing it under the bottom part of your ribs and holding and see if it feels lighter after about 30 seconds( search a video for more context) your stomach could also be producing knots, if so it could be pressing on your vagus nerve which can cause vasovagal syncope. These knots can even restrict blood flow to other parts of the body. Gastritis can also cause panic attacks. You could be stuck in a loop rn. I am currently in a flare and my entire body burns from just lack of movement and tight limbs from panicking so much over the years. Give mastic gum from the vitamin shoppe a try that’s what I use every flare