I learned colloquial Japanese and now I can’t understand anything. Can anyone explain what is happening?

I thought I had a pretty solid grasp of Japanese, but one day I tried to purchase some nail polish at a Japanese drugstore, and the cashier asked me if I needed remover <br><br>I said yes, I need remover (in Japanese)<br><br>The cashier said in English “Do you need remover now?”<br><br>I was confused.<br><br>I said “yes, I can buy it now.”<br><br>The cashier kept repeating the sentence “Do you need remover now?” in English.<br><br>I thought I messed up and tried to rephrase my sentence. But that didn’t change anything.<br><br>At that moment I had a brain fart and jumped from Japanese to English. I said “I’m not sure if you’re asking if I want to buy it now. Or if you’re asking if I need it as well as the nail polish. I don’t need remover with the nail polish, but I would like to buy some.”<br><br>Her face cleared and said “ok do you want it together with the nail polish” and then she threw in the remover. <br><br>Later I tried to make a reservation at a Japanese restaurant and the hostess asked me if I wanted a smoking or non smoking table. I said “smoking please.”<br><br>She said “ok smoking, it **is** a smoking table”<br><br>I said yes, that’s great<br><br>She said “ok smoking, it **is** a smoking table”. <br><br>By this point I was completely confused. I thought I had asked for smoking. I rephrased what I said and she looked at me like I was crazy. I tried to explain that I asked for smoking. She continued to repeat that it **is** a smoking table. I ended up calling a friend who is fluent, and she said "I think you might have asked for smoking (tabako wo sutte kudasai) instead of non smoking (kin'en de onegaishimasu)".<br><br>Whenever I’m in Japan I’ve always had a strange sense of disconnection, like there is a barrier there that I can’t overcome. I jump back and forth randomly, and I get a sinking feeling when I realize nobody around me understands what I’m saying. <br><br>I’m going to Japan in a few days and I’m worried about this.<br><br>Has this ever happened to anyone else?<br><br>&#x200B;