https://newsinhealth.nih.gov/2022/01/it-flu-covid-19-allergies-or-cold
Interesting article with some helpful tips written by the National Institutes of Health (part of the U.S. Department of Health and Human Services).
This article even has a handy grid guide for symptoms.
This article is not intended to be medical advice or to rule out a visit to your healthcare professional; it is provided for informational use only.