Manda

I had arthroscopic knee surgery 7 days ago. Since then, this rash has rapidly developed. So far, I’ve been given fucidin but have stopped using it on the suspicion that it could be atopic dermatitis. Since then, I’ve been taking the antibiotic Sulfatrim DS 800/160 twice daily and using Betaderm cream. I’m not sure what this rash is. If anyone could help me identify it so I know how to proceed - betaderm can make certain rashes worse. Just looking for another opinion, and I will discuss this with a medical professional soon. The image below is my rash as it is today. My possible theory is infected eczema - not sure if it’s viral or bacterial. Any ideas?