If your son can't sleep on the pillow, think of putting the head of his bed up on wooden blocks, even just a 3" angle makes a HUGE difference in drainage and quality of sleep. I hate those nights of just praying your kiddo can stop coughing for more than 30 seconds at a time so he can drop to sleep....sometimes we go back to old school methods to work with the medical stuff......teaspoon of honey, very warm wet cloths held against the chest (like an old fashioned chest plaster), or if the kid gets chilled from the wet when it cools, put hot towel in ziplock bag and hold against chest & one on back (make sure not too hot so no burns), good old vicks vapo-rup on the soles of his feet, hot steamy showers before bed, or sitting in the bathroom breathing in the hot steam before bed....
Ask what options (cayston?) or other med combos are available. Can they try a culture against other meds to see if there are other options? Has the culture changed since the one before treatment, are they able to judge whether the meds are working at all?
Good luck and hang in there. Keep asking questions! If you go for another hospital stay, will they be using different iv meds than the last time? If not, why do they expect it to work this time when it didn't the last? We sat in a program that used ONE main type of IV med for all cf excaberations and when we moved to a new center, were amazed that they treat with a combo of iv meds that actually work against what my kid cultured. Seems logical, but not a lot of centers do that. Does the CF team work with an infectious disease team to come up with the meds plan? Ask again.