I started stuttering 2 years ago and I completely don't know the reason

I started stuttering 2 years ago and I completely don't know the reason I've never stuttered until 2 years ago, I exactly remember my first time, I was at the gym and I felt a block when a guy asked me a question. After that episode, I stuttered at school while reading my homeworks, and then I started stuttering more and more frequently. As of today, I don't stutter when I'm talking to myself; when I'm calm (for ex. when I'm talking to my mom) I feel blocks with the word "non" (which is used in italian for the negative form of EVERY sentence) and I feel a lot of blocks at the beginning of the sentences when talking to people that I'm not confortable with. I'm 18. I read [this thread](https://www.reddit.com/r/Stutter/comments/6uzowb/i_randomly_started_stuttering_and_i_dont_know_why/) and I felt that our problem was similar. Do you think this could be a neurological problem just like you've recommended to him? Thank you guys. p.s.: my stuttering is seriously ruining my life, the fact that I can't say what I'm thinking is so frustrating and this is leading me to isolate myself more and more since I can't have a relation with a person in the way I want. I even had suicidal thoughts in the past (don't worry, I'll never commit a suicide because I know that it's stupid and that's not the solution) Edit: forgot to say that I also feel my heart going very fast when I feel a block.