What Causes Weak Erection,premature Ejaculation And Gynaecomastia?

hi, i m 25 years old.i m facing problem of weak erection and premature ejaculation since the time i remember i started experimenting with my penis.i am also suffering from gynaecomastia. i want to know if these problems are inter-related and if there is any way in which i can come over them in short time.