I'm new. Different type of stutter?

I'm new. Different type of stutter? Hey had this stutter last year some time but i got rid of it but now it's come back. Once i started talking i can talk no problem but sometimes i get stuck when i have to start a sentence with a certain letter or sound. These letters or sound change all of the time and i usually have to work around that sound by saying "oi" or something. Is there a different name for this type of stutter or any tips?