From personal experience it gets worse every time I spend a lot of time on the internet. My theory is this. That because of the quick dopamine surges the internet has to offer the number of dopamine receptors in your brain goes high, meaning there will be less dopamine on your brain as it is more easily absorbed. Also this is unbalancing the serotonin levels making you a bit depressed. With less dopamine you experience all these: http://www.builttoachieve.com/low-dopamine-symptoms-and-solutions/ +stuttering. Don't try to raise your dopamine levels as this will lead to more dopamine receptors and more urges and cravings for dopamine surges. Instead try to befriend boredom and abandon all the activities that are rewarding to your brain like reddit, porn, movies even music. Basically unplug your PC. Do this for a month and see how your stutter goes and generally how your life improves. <3