UK housing options with undiagnosed illness

In September I got ill and had to move back in with parents. This helped my sister, partner and her two kids get their own flat from the council due to over crowding. Could be relevant as my parents also have a council house.

Fast forward to April and I'm still awaiting tests and could have MS which means I need home support such as a carer to help cook and clean. Up until now my dad and sister have been doing so and are pushing for me to declare my sister my carer.

However my sister has 2 kids under 3 years old who make me more ill because their screaming hurts my ears and brain and I end up having to sleep a lot when they are around and have taken to avoiding them in my room (can still hear them though).

I'd like to move out as family discussions have made it clear sister and her kids come before me and parents are against me having any carers other than her as they don't want a stranger poking their nose in.

Do I have any options as I have no money to rent privately (on uc) and would need in home help too?

How would I prove the kids make me more ill to prove this is an unsuitable place to live?

Thanks in advance

Edit I'm f26 if that helps