Technically not TIFU, but today I finally figured it out.

It was a normal afternoon about a week ago and I had nearly run out of salt at home. After my class for my Masters ended, I went for my usual shopping trip at the nearby grocery store. I was about to check out when I remembered I had to buy the salt - I knew the bus was coming soon so I took a quick look, grabbed the cheapest product with a label containing the English word "salt" which looked exactly like salt, and paid for my groceries. I'm a native English speaker living in a Nordic country and my knowledge of the local language isn't amazing, but I knew the word for salt was the same and was pretty sure I had what I needed.

Fast forward a week and my old container of salt has completely run out, so I use the new one to make my usual dish of vegan mashed potatoes and greens (with oil instead of butter, it tastes incredible). A minute or so after I finished sprinkling it, I smelled a very strange smell and felt a sensation in my nose that can only be described as a worse version of the "water up the nose" feeling. I ate a bite and threw away the rest, worrying that the food might somehow be spoiled or that I maybe forgot to wash some detergent off the pan or the ladle. I also noticed that it didn't taste very salty, but I figured I might just have not used enough salt and I'm used to using much less salt in my food anyway.

The day after, I heated up some pre-seasoned potatoes which I consumed without incident, and today, two days after that, I used the same "salt" to season some frozen French fries. As you might guess by now, I had the same reaction. This was getting a bit too weird for me to process on my own at home, so I called my mom and told her I was worried I might be having some kind of reaction to potatoes (my brain initially forgot the normality of the pre-seasoned potatoes entirely). Step by step, I started to put things together and realized that it must have been one of the spices I was using, and the only spice I hadn't put in my food before this mess started was the "salt".

After searching reputable sources to see if any type of salt might cause what I experienced, I started to worry that what I had bought wasn't salt at all. After Google Translate failed to help, I finally used Wikipedia to find out I was right. When I bought it, I had noticed that the label read something like "heart salt" in English; it turned out that rather than sodium chloride, I had bought...ammonium bicarbonate, a leavening agent used in many baking products which can irritate the nose. I was aware of the compound but not of its old name, "salt of Hartshorn", from which the name still used in many Nordic countries derives.

Tomorrow I'm going to go and buy some real salt so that I can enjoy the taste of the food I make again...

TL;DR: bought what I thought was salt but was very much not salt due to a misunderstood translation.