A sudden block

Today morning I was very fluent while talking over the phone with 2 complete strangers in detail. And I was gaining tremendous confidence. My beliefs, perceptions, attitude was very positive. And then it was this guy who asked me a question. I knew him. And then I had this sudden block where I struggled. I immediately wanted to run away and hide. After block, my mind was like why did I block? What happened now? I thought that I had found the solution to fluency. Now what happened? Why did I block again? And then there was a sudden shift in my beliefs, attitude, perception, feeling. I started to become more hesitant, my speaking rate was fast, I was more agitated. I desperately craved for fluency. I didn't want to again get into that phase of blocking.