Funny how some of us can't take it off and others can't put it on.
I have had surgeries with post op complications that lasted weeks and I only lost 2lbs. Frustrating.
Maybe you could up your intake of nuts, dried fruits, root veggies (sweet potatoes, various potatoes etc) and squashes along with more red meats.
I don't like suggesting oily foods, white flour or anything unhealthy but I can put on 10lbs on nut butters, bananas and honey.
Dark breads and butters and pastas in cream sauces work well too.
Do not neglect the question of thyroid...you may just have been kicked up into hyperthyroidism with all of the surgeries and your metabolism is burning things faster. That would require an endocronologist to run some tests and re-balance things out.
Worth checking out if you don't get good results with the above diet.
Sharon