Hello.
It seems you have difficulty sustaining erection, premature ejaculation and inability to achieve erection again after the first ejaculation.
You may be aware of the fact that with age the strength of erection reduces. As per a few reports, the strength of erection can reduce to about 1/4th by the age of 30 and more. This is a natural process. However, the erection should be adequate enough to achieve penetration while having intercourse. If that is a problem, you may have to consult your physician to rule out any medical causes for the loss of erection.
For premature ejaculation, you may have to practice deep-regular breathing, stop-and-start technique, squeeze technique to prolong the time to orgasm. You can read about these techniques. But I suggest you consult your doctor for a better understanding of the problem and the management.
Usually after ejaculation, there is a refractory time for men before they can achieve a second erection. For this to happen there has to be adequate sexual stimulation.
It is vital to maintain good physical fitness for being able to enjoy a healthy sexual experience.
You may also need to explore anxiety issues related to your sexuality. If you are anxious about performing with a partner, please consult your doctor, preferably a Psychiatrist or a Psychologist. Hope this helps.
Take care.
Abhijeet Deshmukh, MD
(This post is for the purpose of providing medical information and is not a substitute for a face-to-face consultation with a doctor. This post is not intended to give or rule out a diagnosis, create a doctor-patient relationship or replace an existing one. I am not able to diagnose medical conditions online. Please consult with your doctor or a qualified healthcare provider for diagnosis and treatment options)