I live in an old condo apartment.
My toilet just backed up. It backed up several times before and I managed to unclog it every time, but it's nothing like I've seen before this time because I don't see anything in the toilet and water is clean. It just takes about 2 minutes for water to go down the drain. And when it does, water is almost completely drained so that water level is below the hole and then it rises back just above the hole. This is unusual since the toilet is normally half full.
I tried a plunger, bleach, and baking soda + vinegar, but no luck. Any idea?
It's really cold here so toilet water is very cold, too, if that helps at all.