My dad is in the same boat. He has deteriorated a lot since Halloween he was kept in hospital on a routine visit a month ago. They told me he has less than 3 months left , he now has pneumonia. Your dad shouldn't be in pain is there a nurse or clinic you can ring about adjusting the meds 

My Dad is going through this as well, he's 73. We only found out two months ago as he started having falls and they found secondary spinal cancer from a primary cancer. He went into hospital for a while but then - as he couldn't walk or move really by the time he had finished in hospital - he went into a really lovely nursing home initially for respite care, but he has ended up staying there. I didn't realise you could get respite care before this! You could ask him if he wanted to try that for a week and see how he found it? They have been so lovely to my Dad and manages his symptoms so kindly and brilliantly as he has got worse. You can also apply for Continuing Health Care funding if he is terminally ill and they will pay all the costs of care homes for you ( not means tested ) which is amazing - you need to get in touch with your doctors or social services for an assessment and referral. Seeing someone you love in pain is the hardest thing in the world