I haven't run into this personally, not have I ever heard of it - but that's not to say we haven't had recurring other infection type things. I have kids with ear tubes (reoccurring ear infections), one has allergies (so reoccurring extra fluid, which led to other stuff when it didn't drain well), we had adenoids out, etc. I think you are very wise to try ENT. They will be able to help you. We found that once we saw ENT - they also are working a lot of the time with allergists and other specialities (much more so than a pediatrician does) so if it's related to something else, they will have heard of it. So I think you will be in good hands, if that comforts you.
Once we were into ENT it was quick to figure out the problem.
Don't worry too much about missing school - at that age, it's ok he can catch up - but I know, it's hard not to worry. He'll be ok.