First of all let me tell you that this is a very commonly seen problem seen in a lot of people these days and hence not a reason to get so much apprehensive and worried about it.
At the same time like any other illnesses in our life, premature ejaculation also has a lot of reasons to occur and it would not be so very easy to tackle this problem virtually or online like this as it needs a lot of time to know the detailed history first followed by counselling's during the treatment phase.
Next Steps
My sincere advice will be to consult a Psychiatrist who can help you to come out of this problem at the earliest.
Health Tips
Never ever discuss these problems with anybody else other than a Psychiatrist as he is professionally trained to handle such issues.