Lump, Varicocele or Cancer?

Hi,

I have had on and off testicular pain for the past few months. I went to see a doctor about it before Christmas and they recommended me for a ultrasound, though the scan is not until Feb 19th

Since then I have had a lump develop on the left side and I’m worried it might be something more serious than a varicocele, like cancer. Should I wait until the 19th or try and get a scan sooner? Is there a way to tell the difference?

Thanks