Thats actually crazy, I also had trouble saying my r's. "Girl" just sounds like "guwl" lol Just all seriousness your "boomerang" stutter makes complete sense and a lot of people who stutter have the same type of experiences until it just sticks for longer and that scares them, causing the stutter to stay for longer. It would be very hard on the mental if you just waited for your stutter to pass while doing nothing. Because, not to scare you it may stay for a long period of time until you deal with the underlying issues. And even if it goes away, it will come back because you don't understand what's happening. Its a lot to explain over text, I have some YouTube videos that explain whats going on and how to treat it. But I don't want to self promote on here so if you want them, feel free to private message me and I'll link you to my channel and help you out