Good evening,
I just wanted to add....very likely the vent tube could have been filled with debris. A hose taken up and run to flush it is what was done for mine. Also some kind of wire gauze or mesh can be placed over it or stuffed in it...to allow the air to escape but discourage squirrels from trying to store nuts or build homes in them. As my guy said he's found a number of squirrel carcasses in them who were trapped and could not get out....causing the blockage...
One vent tube of mine is really odd. When a handyman came out once, I had him look at it. I gave him a long metal pole to jab down there and he came to a point where he could not with all his strength pound through some sort of barrier and when he rose the pole out...it seemed like there was some grit, sandy sort of blockage. Well, this house ALWAYS bubbled since I lived here as a young girl....especially when the laundry drains, the shower, sink, and toilet of the the bathroom in the next room? He was so perplexed that he even asked if my father or I had any enemies that would put some kind of masonary or such? kind of compound down there on purpose. That was a new one for me. I didn't think so. At anyrate...to this day, I still live with that gurgle noise every time my laundry drains. But after reading the above statement from our byc plumber...I may have to look into those chemicals and see if it doesn't help.
And of course it should be common knowledge that feminine products are not flushed. Despite thinking it is common knowledge I often run into this problem at public restrooms...so if you have visitors....sometimes you just don't know.
Hope your problem has resolved itself and does not reoccur. But I would suggest some of the wire gauze stuffed into the vent tube to keep leaves and critters out.
me,
g