I am a PRS adult now, I was born in 1983 with the diagnosis. Most of what you are talking about is related to PRS, the congestion is due to the airway issues, everything tends to make it all bake up, and since he is congested he will breathe through his mouth more which will cause more saliva production, hence more drool. I am 28 and still have constant congestion, most of which is due to allergies, but it aggravates my already small airways and makes for difficult breathing especially at night, drool will be worse at night because of the mouth breathing. The o2 sats while within normal limits, 95 is about normal for someone. But it can never hurt to check with an ENT, I saw one from when I was about 4-5 and still continue to see them yearly to make sure all is well. Since everything is inter-connected ear,nose, throat one problem can affect them all. I am almost always congested due to allergies to dust/pollen so nose backs up, then my ears, and then it all drips down my throat. The ENT would be able to tell you if he will need tubes again, I had them til I was 14, but I still have problems with fluid build-up behind my ear drums occasionally, usually when I have sever allergy flare ups around this time of year. But definitely check out ENT's in your area, preferable one connected to a children's hospital if possible, they will have the best knowledge and expertise with kids.
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