Mystery virus 4 days. head/body ache that went away, dry cough, fever 99.5-102.5, feel rundown. two covid/flu tests neg. had good exam today, told to wait it out. worry is near constant high heart rate 110-130. is this safe if im otherwise healthy?

Your illness does sound viral and will likely resolve as you state. The elevated heart rate is likely due to your fevers and should return to normal when your fevers resolve. If you have persistently elevated HR (without fever), chest pain, or shortness of breath you should see your Dr again promptly. In the meantime drink plenty of fluids. Hope you feel better soon!