Hello~I am so sorry you are experiencing these unpleasant feelings. It sounds to me like a form of low blood pressure called Orthostatic hypotension.
Orthostatic hypotension — also called postural hypotension — is a form of low blood pressure that happens when you stand up from sitting or lying down. Orthostatic hypotension can make you feel dizzy or lightheaded, and maybe even faint.
Orthostatic hypotension may be mild and last for less than a few minutes. However, long-lasting orthostatic hypotension can signal more-serious problems, so it's important to see a doctor if you frequently feel lightheaded when standing up.
Occasional (acute) orthostatic hypotension is usually caused by something obvious, such as dehydration or lengthy bed rest, and is easily treated. Chronic orthostatic hypotension is usually a sign of another health problem, so treatment varies.
It's important to see your doctor if you experience frequent symptoms of orthostatic hypotension because they can signal serious problems. It's even more urgent to see a doctor if you lose consciousness, even for just a few seconds.
Keep a record of your symptoms, when they occurred, how long they lasted and what you were doing at the time. If these occur at dangerous times, such as while driving, discuss this with your doctor.
You have symptoms of orthostatic hypotension (also called orthostatic intolerance). Orthostatic hypotension is a form of low blood pressure; the blood vessels do not constrict (tighten) as you stand up. This condition is usually a symptom of an underlying condition rather than a disease in itself.
The drop in blood pressure reduces the flow of oxygen to the brain. Symptoms include dizziness, lightheadedness, altered vision (blurred vision, white outs, gray outs, black outs, double vision), fainting, anxiety, exercise intolerance, fatigue, headache, heart palpitations, sensation of difficulty breathing or swallowing,
sweating, weakness, nausea, mental confusion, muscle tremors, hearing disturbances (including impaired hearing, crackles and tinnitus), pain in the neck/shoulder, low back pain.
There are numerous reasons for orthostatic hypotension such as dehydration (eg: due to vomiting, diarrhea), fever, anaemia, diabetes, adrenal insufficiency, prolonged bed rest, hypothyroidism, autonomic dysfunction, significant blood loss, heart problems, medications, anxiety and panic attacks, acute hyperglycemia, hypoaldosteronism, hypokalemia.
I personally had orthostatic hypotension due to untreated hypothyroidism. I did have anxiety from hypothyroidism but from many other conditions as well such as magnesium and vitamin B12 deficiency. I can recommend magnesium, B vitamins and ASMR videos (check on youtube) to help with anxiety. :)