Hi. I hope you find a provider that has at least read something about post Covid syndrome. Symptoms are in the medical news regularly. At this point there's no real excuse for a medical professional seeing patients who have had COVID virus and report continued symptoms to be ignorant of the common medical symptoms and abnormalities that develop after in a large number of people.
I'm not a doctor or equivalent and it sounds like you have not been seen as a post Covid patient. I hesitate to appear to give you advice but I will tell you this: rapid heart rate is a condition that manifests often post Covid. It can be associated w blood pressure abnormalities and inflammation. This is well known. The medical literature says severity of the virus - great or mild- is NOT a determinant for Post Covid Syndrome (now renamed). Unfortunately you are going to have to read information for yourself. Begin here. There are many posts discussing your very symptoms.
So you'll understand you have company even if your current Dr does not acknowledge you for this. Then read reliable sites that come up on Google searches like Mayo, WebMD etc under "long COVID" "post Covid". You'll learn about your symptoms. You need to understand that for yourself.
You indicate you are seeing many Drs. Do you have diagnoses for any of your symptoms? Are your Drs including cardiology +opthalmology?
I think it's safe + wise to be taking substantial doses of gelcaps Vit D3. An individual supplement. It's greatly anti-inflammatory. Also VitC is essential in amounts more than is in some negligible multivits. B vits and quality high level probiotics are also an important part of post Covid. These are stand-alone supplements you take. These address basic health foundations which are needed post Covid.
I'm not addressing the brain fog etc but you know that caffeine does increase fast heart rate. So limit it. And make sure you have a lot of fluid intake. Your body needs enough fluid volume. We fall short often as Seniors
You may want to invest a few dollars in a pulse oximetry. That's the finger monitor if your heart rate+ blood oxygen level. And a home blood pressure cuff is another basic essential. They are available at Walmart, Amazon etc. You will find out more about yourself when you have a daily log of these measurements. They're very important.
You age is not a problem. Drs responses to your age however may be. Perhaps find a primary doctor who specializes in older adults.
Please pursue looking after yourself where you may not be by Drs. You seem to be having post Covid extending symptoms. My suggestions should help start you in the right direction but they are not a substitute for a medical determination of medical conditions, which seem related + presented after you had the virus.
Let us know what you're doing for yourself+ the results you're getting. You can't just let it go.
Blessings.
🙏❤️🧓