Stuttering only on words that start with an "ah" or "eh" sounds?

Stuttering only on words that start with an "ah" or "eh" sounds? Hi all, I've had this thing for years, but pretty much ignored it 'since it didn't happen as often in the past. But in the past few months, it's happened more often and impeded my ability to communicate. So I often stutter, or have difficulty in pronouncing words that start with "ah" or "eh" sounds, like "anyone", "everyone", or "are you okay?", etc. Like I could say a whole sentence smoothly, until the word "anyone", and my tongue just couldn't produce that sound. I had to really concentrate and tried very slowly in order to say that word. When I'm relax, I could say those words alone (without a sentence) without a problem. But when I put them in a sentence, my mind got tensed up and I stuttered with them. I never had speech impediment growing up. When I was younger (I'm 30 now), it rarely happened. But I've had it more often lately. I'd like to do more research on this problem, but I don't even know what it's called. Can anyone give me some more information on my condition? Tips or advice are greatly appreciated. Thank you.