@Bel, sorry to hear you're having trouble with seromas again. They are awful & so painful! I had a large seroma that kept building up after my mastectomy in April last year. I had it repeatedly drained but I had severe cording as well that went from my wrist to my waist, so I was referred to a brilliant lymphoedema specialist who used laser and massage to resolve it over a few months. I have had 3 further surgeries since then and since my hysterectomy in May, my arm is having fluid issues again so I'm now wearing a sleeve. Surgery certainly can flare up the lymphatic system. It's the body's automatic response to inflammation of any kind. I suggest you visit a lymphoedema physio and see if you can get some help for your seroma. They are amazing what they can do.
All the very best.. SJ