dear ashraf

first of all sorry fr the delay in reply , was on vacations!!

-well your question - - do you think that any physio specialist can do mobilization to the disc - or that needs and extremely professional one and expert in that (as it might be very dangerous)

1- my honest answer would be that you need a good physio to treat you but a really good physio to assess you and chart out the actual problem. i was going thru things you wrote
2- william flex ion ex would be a definite no from me if its a true disc, now early morning lumbar fascia stretch as mentioned in sturt mcgill is a different story,that does not involve lumbar movement
3- most physio do a maitland mobs on the spine this shud not be misunderstood with FIXING THE SPINE theory like chiro or osteos, it is mainly targeted at improving the range of movement ,
4 - core muscles like your trans.rectus abd , multifidus, iliopoas , are important to stabilize the spine and hold in right position
5 - work station evaluation is generally done by physios specialised in ergnomics and work place safety , in general the most important thing is to know if you are having proper weight distribution thru your body ,also the golden rule is not to sit for more than 30 min . thats my advise to everyone , also if u can replace the chair with a swiss ball it works well....

hope i ve of help
regards

ben