Hello and thanks for your query. From the description of your problem, it appears that you are suffering from a sexual problem called Premature ejaculation. The most common cause of premature ejaculation is anxiety (known as performance anxiety ). So, the first advise I will give you is to stop becoming more and more anxious and worried about this problem. Also, very often, a hypersensitive response of the penis can also result in quick ejaculation. To overcome this, I will suggest that you practice the following sexual techniques regularly: 1) In the stop-start technique, the penis can be stimulated (by masturbation) till a point when you feel close to orgasm. Then the stimulation is stopped for a while and again the process is repeated a few times. 2) In the squeeze technique, the penis can be stimulated (by masturbation) till a point when you feel close to orgasm. At this point the lower part of the head of the penis is squeezed tightly with the index finger and thumb around for a few seconds till the erection decreases. Then the stimulation can be restarted and the process is repeated a few times. Alternatively, there are medication like Dapoxetine that are available which can help delay ejaculation time. So, if this problem is very distressing, I would suggest that you consult a doctor for further help and treatment. Regarding you last question about the dark colouration of the penis, I would like to clarify that this is normal. The genital area is always more hyperpigmented that the rest of the body. So, you needn t worry about this. Regards, Dr. Jonas Sundarakumar MBBS., DPM., MRCPsych.(U.K.) Consultant Psychiatrist