Dad has weeks left small cell lung cancer with brain mets

My dad was diagnosed last august with small cell lung cancer, which had spread to the spine and lymph nodes. In feb this year he was told he has multiple brain tumours. He is now unable to walk, he's at home in a hospital bed with carers coming in each day. He started being sick the day he needed the bed, but is now on anti sickness tablets so he isn't suffering with this now. He's eating less, still able to get to his commode himself but with a struggle. The nurses said he has weeks left, but I don't know if that means it could be up to 4 or more? Like when do they stop counting it as weeks and as months? Might sound silly but I want to know how long 'weeks' could mean. I mean could 6 weeks still count..? I would think of that as months though if it were that long..I've found this all such a whirlwind, dad was so strong but said to me 'I'm losing the fight now' which broke my heart. I live 4 hours away from my dad and did a visit recently which was lovely but such a mix of emotions. Really struggled to get actual quality time with him, I'm struggling to plan trips and life around this unpredictable horrible disease.

If anyone has experience with this, being told there are only weeks left and can tell me their stories I would find that helpful, I am mindful that every patient is different though as I've been told many times!