Hi, I wanted to see if anyone else have experienced this and what the outcome is. I'm sick with worry and want to know if I should be preparing for the worst

A week ago I found a lump on my chest, just below my collar bone and alongside my sternum. I went to the Dr's and she has referred me for an urgent ultrasound, which is taking place in a weeks time. The lump feels gard like bone, doesn't move and isn't painful to touch.

The lump was 2x2" when I found it but it has now grown to 4x2", going across my sternum. I rang the Dr's but they said there is nothing they can do until my scan is done. The Dr didn't give me any reassurance in what it could be so it had left me feeling quite worried. 

I have recently lost 2 stone the past 5 months, and lately I have been feeling very nauseous. On 2 occasions I have experienced numbness/pins and needs in my hand.