Sorry to hear this. Initial advice is to try not getting into the habit of substituting words and to not worry about it. What I'm saying is, don't make a stutter a habit. Make sure you're getting enough sleep, prepare your sentences and try to spot trends in when you're struggling the most. i.e. do you normally block when you're meeting new people? When people are expecting you to respond to something? If you do spot a trend, you can work on fixing it.