Acute tracheobronchitis, croup, stridor, RSV. Thought to be what I have. Normal chest X-ray, CT scan normal blood ox normal. Help. What test do next?

Possible rx. If you have an acute infection, the symptoms most likely will resolve without need for further testing. If you have had symptoms for three or more weeks, a secondary infection, antibiotics may be used to treat a specific bacterial infection; prolonged inflammation is treatable with aerosolized steroids. These are some possible management options.
Get treated. Likely post viral and possible secondary bacterial it has been a "bad year" for upper respiratory problems and they have lasted forbseveralmweeks you are lucky that these tests are still ok- but you may not clear without medications and time.
Consult your doctor. It is not uncommon for chest xray and ct to be normal in mild cases. Your primary care physician may suggest further evaluation with blood tests. Rest and supportive care should help. If you are asthmatic, bronchiodilator may be needed. Antibiotics may be needed in some cases.