Probably not the blockage affects the breathing, but the breathing causes the blockage. Probaby you try to tell everything in one breath but noone tries to talk like that. Or you just want to tell everything fast. Or you just focus more on how you talk when you are under stress. Whatever the case is. I recommend you to focus on improving your breathing. Remember to breathe when you talk. You can search something about abdominal breathing in google. It has lots of benefits. The way I practice it (which I already shared here) works for me. Please share your experiences after, if you try it.