Hello,
Sorry to hear about your situation, but I believe that it is very much possible to solve your dilemma.
It is possible that the physio's may be cautious because of previous lipoma, however, they may not know that lipoma which can develop in any part of the body, particularly beneath the skin, seldom give any trouble beyond that connected with their size and position.
I think you should get this confirmed from a dr before anyone considers providing advice here.
It may be necessary to try some more 'esoteric' modalities of physiotherapy to ease your problems (ex. acupuncture).
Additionally it would be helpful to know whether or not you mobilised the left side over the period of surgery. The thoracic cage like any area of the body is just as prone to stiffness, adhesions, scar tissue build up, and soft tissue changes.
For example: are you able to fully expand your lungs from your abdomen?
Being able to achieve this alone may contribute to 'better' thoracic movement and contribute to localized improvements in soft tissue repair.
Just some things to consider,
Regards