Your priors should be remarkably different now vs. last February. At the end of February the U.S. had 60 active reported COVID cases. Assume a 10:1 underreporting and that's about 600 total cases, then assume about 100 million cold + flu cases at any given time in the winter and there's about 200,000:1 odds that a given respiratory illness was actually COVID.
Now there are 4.1 million active COVID cases in the U.S. Assume a 5:1 underreporting (we're better at testing, but still seeing close to 50% test positivity rates in the Midwest, worse than NYC at the peak) and that's 20 million active cases. Meanwhile flu cases have dropped by ~90% [1], so if we assume that holds true for colds as well, estimate about 10 million active cases of cold & flu in the U.S. A random respiratory illness with no further differentials then has a 2:1 chance of being COVID.
Obviously things like location, differential diagnosis, etc. will change those odds. A random respiratory illness in the Bay Area (where COVID numbers are low and we just had a bunch of wildfires) is most likely to be allergies or smoke inhalation, while if you had a random respiratory illness in NYC in April there was a decent chance it was COVID. Given the OP's differential diagnosis though (rash and shortness of breath are way more common in COVID than bronchitis or flu), it's not unreasonable to conclude he has COVID.
Now there are 4.1 million active COVID cases in the U.S. Assume a 5:1 underreporting (we're better at testing, but still seeing close to 50% test positivity rates in the Midwest, worse than NYC at the peak) and that's 20 million active cases. Meanwhile flu cases have dropped by ~90% [1], so if we assume that holds true for colds as well, estimate about 10 million active cases of cold & flu in the U.S. A random respiratory illness with no further differentials then has a 2:1 chance of being COVID.
Obviously things like location, differential diagnosis, etc. will change those odds. A random respiratory illness in the Bay Area (where COVID numbers are low and we just had a bunch of wildfires) is most likely to be allergies or smoke inhalation, while if you had a random respiratory illness in NYC in April there was a decent chance it was COVID. Given the OP's differential diagnosis though (rash and shortness of breath are way more common in COVID than bronchitis or flu), it's not unreasonable to conclude he has COVID.
[1] https://www.cdc.gov/mmwr/volumes/69/wr/mm6937a6.htm