Hi,
Thank you for posting your query.
Yes, your 
back pain is a part of your old sciatica, due to 
disc disease in the lumbar region.
you should continue back extension exercises under the guidance of a physiotherapist. In addition, IFT and 
ultrasound would also help.
If pain is severe, you may take 
diclofenac or 
ibuprofen for pain relief.
There is no need to worry at present.
I hope my reply has helped you.
I would be pleased to answer, if you have any follow up queries or if you require any further information.     
Best wishes,
Dr Sudhir Kumar MD (Internal Medicine), DM (Neurology)
Senior Consultant Neurologist
Apollo Hospitals, Hyderabad,
For DIRECT QUERY to me:  http://bit.ly/Dr-Sudhir-kumar 
My blog: http://bestneurodoctor.blogspot.com/