Hi guys,
I am a sports training and physiotherapist from India. I agree with what alophysio is saying. We need get into the root of the problem. Using electrotherapy would only relieve you of the symptoms, but the problem would come back. Core training for this individual is very important, with attention to be focused on TA(transverse abdominus) and gluts tightening, as it will prevent instability while doing exercise and prevent further damage to the back. Flexion exercises can be done, but with care. Maybe we can check for gluts and hamstrings tighening also ans stretch it if needed. I hope i made some sense, as it is my first post.
Cheers.