Dad has been in emergency room or long term care 4 months now; we are using his lifetime days now; need advice for next steps and how to pay.

My dad has COPD. His wife passed almost 3 years ago and he has been depressed and his health has been declining since. I am his only daughter and caregiver trying to do my best to take care of him in his last few years. He has been in and out of the hospital since Nov 2017; this last time he went in a few days prior to thanksgiving 2019 and was diagnosed with pneumonia. He started in ER, doctor suggested we insert a trach and feeding tube; he went to an LTAC for further rehab/nursing help. After 36 days they could not get him weaned off the ventilator so they sent us to Denison (did not want to drive downtown Dallas) to 'slowly' wean off the vent. He ended up in the ER less than 24 hours after he got there because he was way to sick to be in a skilled nursing facility - per the pulmonologist seeing him at the SNF. Spent 16 days in the hospital (they got rid of the pneumonia and weaned off the vent!) and now we are back to the LTAC for further rehab. My problem is I know approximately how many days he has used; but not sure what to do when he runs out of the lifetime days; nor if they will accept him at the next place due to his complex treatment. Anyone have any experience with Medicare and what to tell them? and will they work with you?