Brief Answer:
you need to get clinically examined and investigated thoroughly ..

Detailed Answer:
Hello XXXX, Welcome to HCM,

I've gone through your query and understand your concern,

Based on your description and severity of the symptoms, the first thing to rule out is any element of pulmonary embolism as you're having several risk factors like chronic AFIB, blockage of vein already on anticoagulant..

Along with it, there's a need to evaluate any underlying angina, as those sudden pressure symptoms along with chest discomfort and "Symptoms lessen if I sit for 20+ minutes" - has to be investigated and clinically examined..

Recurrence is a quite concerning factor, specially since it's happening 2 to 3 times a month..

Headache is also another concerning factor, as it indicates there's either disturbances in blood flow and/ blood pressure, so those medications may be needed to revised and optimized..

So you need to get in touch with your doctor (preferably Cardiologist) for thorough clinical examination along with a battery of investigations (i.e. 12 lead EKG, stress test after obtaining fitness for it, myocardial perfusion scan , Chest X-ray along with ventilation/perfusion study of the lungs, PT/INR, BUN, Creatinine, 2D-echocardiogarphy with Color Doppler and/ CT pulmonary angiography and a few more depending on the findings) at the earliest..

It looks a lot of investigations, but indeed they are required for a complete evaluation of the present symptoms..

Feel free to let me know if you're having any further queries, i'll be glad to clarify..

Let Me know how you stay in the due course..please don't delay the check-up any more and get it done without any further delay to avoid any major complications..

Take Care
Kind Regards

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