I’m sorry that happened with your teacher. Sounds frustrating. From your description, you may have some vocal fold dysfunction going on along with your stutter. Basically that’s when the vocal folds (in the voice box) close up or partially close during breathing- which disrupts regular air flow. I would definitely recommend a speech therapist who specializes in stuttering and/or voice. I’m an SLP and I’ve had a number of clients who experience this while talking and/or during exercise as well. Usually breathing exercises are helpful in the moment- here’s a good link: http://miparentedge.org/wp-content/uploads/2014/10/Breathing-Exercises-Handout_ChrisMcCurry.pdf (It is aimed at parents but the techniques are good for anyone)