Can a sore, smooth, free moving lump ever be Malignant?

I have 3 lumps and am waiting for the hospital appointment to do an ultrasound but can't stop worrying about it. I have two on my chest and one on my lower back, the ones on my chest are abou the size of a chickpea but don't hurt, the one on my lower back is very painfull although it feels exactly like the others to the touch; the doctor said they are just lipomas (benign) but still he has booked a scan and when i researched lipomas i could not find anything about painful ones, in fact whenever i entered pain as a search term all that appeared was cancer.