I cant say words that start with T G or K

I cant say words that start with T G or K Im a 15 year old boy, and i have a problem when i speak. When i try to say words that start with letters like T, G, K, i just cant. Something is stopping me from saying that word and this problem really impacted me. I dont usually stutter when im relaxed, at home or friends, its usually at school, when im reading something outloud. (Mostly i read in English class, and English is not my first language). So can i somehow fix this issue? I really dont want to seem weird in class and i have avoided reading when i can. And also when i try to force out the word, mucles in my face tighten, and my face looks very weird, and i just stop for a second, breath in, and try to say the word slowly. If i cant fix my problem, can i atleast avoid it somehow that doesnt affect me getting lower grades and seeming weird? Thanks.