Hi well we are not doctors on these forums but I am a microbiologist. I can try to give you some advice. Sorry you had trouble getting help on the other sites. It sounds like a staph infection. But You really need to get it cultured if they didn't do that. That way if this antibiotic isn't working you can find out if the bacteria is resistant to what you took or if something else is going on or if there is more than one infection. So that is what I would do. Usually, yellow crusty itchy things are staphlococcus infections. But, sometimes it is hard to tell by color alone. So, don't touch the area or you can spread it easily. Wash you hands. You can put triple antibiotic ointment on it on the outside for now. I would see another doctor, perhaps an infectious disease specialist if you can get in right away. Or go to an urgent care just to get them to do the culture. They could take a sputum culture as well if they listen to your lungs and it sounds bacterial. It could be viral in the lungs. They can do an xray to see if it necessary to rule out pneumonia.
Hope this helps. Feel better.
mkh9