Exercising when sick may not always be the best idea. Trying to sweat it out may sometimes make it worse. The general guidelines should be;

Know your body: You should know when you really shouldn’t workout. If you’re getting light headed, can’t breathe, headache, diarrhea, vomiting, joint or muscle aches, or have a fever avoid exercising.

Once these symptoms begin to fade, then you can start returning to exercise with modified intensity as needed. 

https://www.webmd.com/cold-and-flu/features/exercising-when-sick#1

https://www.precisionnutrition.com/working-out-when-sick