Hello and Welcome to HCM,
Thanks for writing to us.
From description it seems to be soft tissue injury
. Lump might be due to haematoma
formation(collection of blood).
You need an x-ray to rule out any bony injury.
I suggest you to consult an orthopaedician nearby for a detailed examination. You may get the X-ray of the area affected under his/her guidance.Meanwhile apply ice to affected area and take anti-inflammatory drug like motrin
to reduce pain and inflammation. Avoid forward bending and rest well.
Hope this helps you.
Wishing you good health...
Dr Saurabh Gupta.