Hi,
As far as managing a discogenic back problem, a physiotherapist should assess your range of movement, and have a good feel of your spine (that's like localising a bone in your spine and testing it for movement) it to assess the movement of the segments... this will give an indication of tight/loose structures, tension in musculature, inflammation, pain response, and normal/abnormal movements around the joints. They may also assess your spine in different postural positions which allows them to isolate problems or movement patterns that need addressing. The physio should also assess your core strength (through activation of your transversus abdominus muscle - your core acts to support your lower spine in every day activities), and other muscle strength around your pelvis which supports your spine.

Treatment with electrotherapy such as ultrasound and heat can be useful in some amounts but it should not be your whole treatment. With all respect to honest physios out there, i would be very dubious about a physio that just plugs you into a few machines for 15 minutes as the main part of your treatment program.(!!)

From your explanations it sounds like you need an exercise program to regain normal lumbar spine movement patterns, work on your core strength and continue this as a maintenance program long-term.

As for a workplace assessment, this means looking at the workstation set up you have such as chair suitability and size, lumbar support, computer monitor height, keyboard reach distance, mouse reach, phone reach... etc etc. Your chair at work should be wide enough in the seat to accommodate your bottom without oozing over the edges, but nor should you be swimming in the middle of the chair. The back support on your chair should be fitted into the curve of your back and the seat tilt should be level or slightly tipped forwards. your feet should be able to be flat to the floor comfortably with your bottom back in the seat. If your chair isn't adjustable to suit, i would suggest taking a towel and rolling it up to put into your lumbar spine when you are sitting for support. it will help prevent you from slouching (slouching will exacerbate the disc problem).

May I suggest seeing an alternative physiotherapist for second opinion - try one who is trained in McKenzie and pilates (core strength).

Good Luck
msk101