Brief Answer:
Causes listed, few remedies for the meantime

Detailed Answer:
Hello sir and welcome.

Thank you for writing in.

I would like to start by letting you know that there are many causes for sudden reduction or absent sensation on the penis head. For your reference I shall start by first listing these causes:
-Pudendal nerve block or entrapment
-Circulatory conditions
-Medical conditions that result in circulatory problems (eg. hypertension) that affect blood circulation to the penis. Blood circulation to the penis is what helps in erection, and sensation; any problem with circulation can cause such a presentation
-Injury or trauma (especially seen in bicyclists; and injuries to lower back which is the part that supplies the pelvis/penis)
-Other medical conditions like diabetes can also reduce sensation

The reason why I have listed these conditions out for you sir, is so you understand how there can be many causes to your problem, and all these causes are treatable; but need to be accurately diagnosed. So in my opinion, it would be best to visit your doctor for a physical examination backed up with a few investigations to find the exact cause. Once the cause is found, complete recovery will not be far away.

I hope I have helped with information that should guide you through management and in time complete recovery from your problem. In the meantime, you can also try to wear lose and comfortable undergarments, avoid physical activities that can cause injury or trauma to the pelvis and also go about daily gentle massages in and around the pelvis/groin region.

Wishing you lots of luck. Please feel free to write back to me for any further clarifications, I would be more than happy to help.

God bless.

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