again. and again?

So what is wrong with my drain? It happened again. At least this time I did not have to do a toilet wash. Thankfully. I poured water with caustic soda in the drain as last time and I think I inhaled a bit to much of that nasty gas. No worries, nothing happened so in that sense it was not too much. But I started coughing and had to stick the head out of the toilet a couple of times. Eventually I got it all in the drain. The next morning it was working properly again.

So what? This is going to happen every four months? I should talk to the girl I am renting from and ask if she ever had this problem. Who knows if the caustic soda will help in the future. I do like being able to take showers.