Mine had blocked tear ducts at one point, and what I did was I rubbed the spot between her eye and her nose, many times a day, and I wiped the gunk off with a warm, moist paper towel (it's probably better to use a washcloth, though.. saves trees ^.~) It took two days to clear it out.
Other things I found when I researched on the web was to squirt a few drops of breastmilk into the corner of her eye where the tearducts are, and there are even special drops (though i think the dr has to prescribe them) made from boric acid, i believe, you can drop into their eyes.
I dont know about the redness, maybe your baby just has especially tiny tearducts so it got really irritated. I'd say it might be an infection but since it only happened that one time, and you've brought it up multiple times to your dr, I don't think that's whats wrong.
I do also know that once you get it unclogged, however it may happen, it can happen again, so don't panic if it does, just keep doing whatever fixed it last time.
Mine hasn't had it again though, so maybe yours will get lucky too. I wish you the best
Oh, and if I were you, I'd get a different dr. He/She has no right to be paid for keeping you in the dark about your health concerns for your little one. He sounds like he's just going to wait until a year and tell you about the surgery they can do to fix it and not give you any other options.
Wow, I'm really forgetful today... Also, it is possible for babies to develop allergies they didn't have at birth, though I don't think that's what's going on here. Still good to keep in mind though.