Safety Of Percocet And Morphine?

My husband was recently hospitalized for multiple pulmonary embolisms {in both lungs}. He has had an as yet undiagnosed lung disease going on 10 months now, 13 times in the hospital. After this last time they sent him to 10 days inpatient pulmonary rehab hoping to stop the revolving ER door. The doc there put him on Percocet {oxycodone 5mg/apap 325 mg} every 4-6 hours and morphine sulfate IMM REL 15 mg in between every 4 -6 hours.
They released him Friday night on this dose. My husband is complaining that it is barely touching his pain. He has asked me to give him more but I will not, especially since he is on home oxygen and bi-pap. He understands, it’s just that his chest hurts so bad.
Could he have built up such a tolerance this quick? And is this dosage even safe? He was on dilauded and percocet and fentynyl in the hospital. He hates the drugs because he feels so out of touch but his pain is so bad. This is really frustrating.
I will take him to his private doctor monday morning but in the meantime what should we do? The last thing we want to do is another ER trip.