Thank you for your question.
You do not mention if the problem started quickly?
In young men, both premature ejaculation and the accompanying erectile dysfunction is a learned problem. It is a very common problem and is compounded by boys learning to masturbate under censure or secrecy. There are no 'quick' fixes to unlearning bad habits and cultivating good ones where pelvic floor exercises and masturbatory exercises are practised daily to learn to delay gratification I.e ejaculation.
Please refer to Metz and Mc Carthy, Managing premature ejaculation for masturbatory exercises. It may take 4-6 weeks for some control to be regained.
hope this helps