What is the ruling on combining and shortening prayers (al-Jam' wal-Qasr)? And do the rulings of travel cease for a sick traveler who is hospitalized for a long period outside his region?

If the travel distance is 83 kilometers or more, but you intend to stay for more than four days, then you must complete the prayer and are not permitted to avail yourself of the concessions for travelers, because you are considered, in the view of the majority of scholars, to be in the status of a resident. As for the prayers you shortened previously, you are not required to repeat them.