Why is my 18 mo old having so many sinus problems?

My son has had a runny nose since he was a month old. He ended up having 6 ear infections in 5 months and had tubes put in Aug 2 (@ 13 mo old). He had a couple of sinus infections before the tubes but they are becoming more frequent, for instance he just finished an antibiotic for this sinus infection Thursday. Saturday morning the snot has started running out of his nose and he feels bad again. He is even on an antihistamine (Zyrtec) 2.5mL daily in an attempt to dry him up. His primary doctor said when he goes for his 6 month tube check-up to talk to the ENT about having his adenoids taken out because they swell and prevent drainage from exiting the sinus cavity. His throat looks weird, almost spongy, but the doc said it's from the drainage. It's been that way since about November. The check up is for the ENT is Feb 8. If anyone has any ideas of what to ask the doctor when I go it would be much appreciated. If you have any advice AT ALL it would be appreciated. I just feel so bad for him and so helpless at the same time, I want to do my best for him.