Do you feel lack of concentration while speaking and doing something else?

Do you feel lack of concentration while speaking and doing something else? When I try to speak, especially when I block and my head twitching, I can't concentrate or focus doing something else (e.g. driving or reading something very short, e.g. a signboard). My eyes gets a little bit blurry. To focus again I must stop speaking, recover myself for a couple of seconds and continue what I'm doing. I stuttered my entire life. I don't know if this is just me, because I stutter or it's irrelevant. What do you think? Best.