Thanks for your query.
See the pain described by you seems to me as a complication of appendix
surgery probably due to nerve irritation
. Consult your surgeon and get yourself examined in details. Again this pain may arise from the spinal cord
itself. Pain may be due to nerve root compression
due to age related degenerative disc changes. So better you should undergo a MRI of spine specially the lumbar region and hip joints.
Hope I have answered your queries. If you have further queries you can write back to me.
Dr Arnab Maji