I have exactly the same, i cant speak vowels at the beginning of a sentence. Its not my tong i think, i just cant say it. I deal with it in a few ways: 1. I breath all my air out and then say it idk why but it works, downside is that you sound out of breath whike speaking. 2. I avoid those words. I got so used to it that i can chose my words carefully when im in an conversation. Even when preparing a presentation i try to avoid vowels at the beginning of a sentence. I see that you posted this 2 years ago, please tell me if you have found better sollutions because i am still struggling everyday with this.