what is this lump help please no previous trauma.
Seems to be a growth...
It seems like a growth there. If there was a scar at this location - it either could be a hypertrophied scar or keloid. But as you mentioned there was no trauma involved in the area, I would rule both those out. Now the growth could be arising from under the skin, fibrous tissue (fibroma) or the bone (osteoma). Fibroma seems more like based on the initial appearance. I will consider local examination by a surgeon followed by an ultrasound scan. If deemed necessary excision biopsy may be performed.
Hope this helps. Let me know if you need clarifications.