Lump in my groin

Hi,

 

Earlier on in the year I felt a lump in my groin while showering. I'd try and feel for it again but some days I wouldn't be able to feel anything. Then july/August time it's got much bigger and there's no doubting it's there now. I went to the doctor's on the 1st August and asked to be referred, she didn't seem concerned at all not even when I told her how long it had been there. I have an ultrasound sound booked for the 27th September, I'm so anxious about it. The longer i wait the more worried I am. It does hurt, well almost ache most of the time. Should I be worried?