I Have An Infected Cyst On My Neck And The

I have an infected cyst on my neck and the doctor prescribe flucloxacillin 2 days ago but still no improvement. I have had the cyst checked when it was normal and it wasn't cancerous or anything bad however with the infection now it is very swollen and sore and I am very concerned about it. when should I start to see improvements and is there anything else I can do? I am also meant to be flying interstate this weekend, will the air pressure with flying hurt it?