Hi! ((hugs!!))
First, adenoids out is not really considered "major" surgery. Just wanted to throw that out there for those responders who called it that.
My now three year old had two sets of tubes and his adenoids out. I will tell you that, while the surgery was only 20 minutes long, it was a lot harder on him than the tubes. He really had a hard time recovering for the first day, and the second day was not that easy. After that he was much better, though!
He still gets occasional sinus/ear infections, but now they're more like twice a year instead of three days after he went off the antibiotics from the last one.
Second opinions are fine, they never hurt, but after two sets of tubes haven't helped I'd sure want something done!!
Also, across-the-board allergy testing isn't a bad idea either. You have to ask your ped to recommend them so you can get the referral. My son came back allergic to absolutely nothing, though. Go figure!! But if it were to be caused by an allergy it sure is nice to find out now, so you might decrease those infections and therefore the amt of antibiotics!
I also highly recommend probiotics. The antibiotics clear an infection but can leave the body stripped of the good bacteria that fight infection. Probiotics are available in the drug store or any vitamin shop.
:)