Why do they want me to give extra info on a condition that will never get better? It feels like bullying

I have been dealing with MetLife since Oct of last year. I have a 2 Level Fusion at S1 to L4 a neck fusion at C3. I also have DDD Spinal Stenosis and S1 Joint Dysfunction. I can not sit or stand for long periods of time without major pain in legs and lower spine. My job is a Call Center Rep and sitting for long periods at the time is a major part of my job. Why do they make me give extra info on a condition that will never get much better? I feel as though I am being bullied? My major complaint is they paid me STD for 5 months and then needed medical info with x amount of weeks until LTD kicked in and stopped payment. Hey I’m broke and have no money for medications let alone a DR visit… This has happened in 2 month intervals and then the decide to pay. Much distress when you are unable to work your job due to chronic pain…