Thankyou for this post. During this pandemic there is many people that are alone and your post highlights the adverse effects of that which others will be able to relate to.
I'm married and retired, so rarely alone. When my wife leaves on the rare occasion without me I tend to raid the chocolate draw so being alone isnt good for me. Lol. However, I can understand your frustration and moreso fear, of what will happen if you fall very ill. Your fears are not abnormal in any way.
It's really good you've had blood tests because blood tests and the like can find issues not thought about. My wife has been sleeping every afternoon for 12 months and last week found the cause- diabetes. So it is a good idea getting such support.
Feeling dizzy is a major worry as head trauma often occurs when fainting. The first feeling of dizziness you should lie down and raise your feet. This allows blood to reach your brain quickly.
Take your phone everywhere with you. Even make a holder on your wrist for it or similar.
If you havent already become an ambulance subscriber. That will take away the worry if you need one as they can be quite expensive if needed.
Other general actions is drinking lots of water and befriend neighbours. This is what elderly people do not unlike yourself that have the same fear of the ramifications of living alone.
I hope your tests come back ok. Regardless we are here 24/7/365 and again welcome to the forum.