Hello Brandon,
Thank you for your query at DoctorSpring.com
I have read your query and I understand your concern.
Currently you're experiencing light headedness, muscle fatigue, and chest tightness.
There sre no possibilities of post viral syndrome, since there is no active signs of infection.
You need to get a few investigations done :
1) CBC - to rule out anemia. ( common cause of the symptoms you're having )
2) Serum Electrolyes - to rule out electrolyte imbalance.
3) Serum Vitamin B12 levels.
4) ECG.
The most probable cause is anemia, however the blood examination will be able to give a much better picture. Is there any history of fever or chills? You also need to get your BP checked when you're going for the investigations.
Kindly get back to me with all your reports, and i will be able to help you further,
Regards.