Brief Answer:
A most elaborate evaluation to find the cause, most likely ones listed

Detailed Answer:
Hello sir and welcome.

Thank you for writing to us.

I have gone through your query with diligence and would like you to know that I am here to help. Let me address your query in 2 parts:

1. Loss of penis sensitivity, whether gradual or almost sudden can be related to a number of causes, which I shall first list out for you:

+Poor blood circulation due to conditions like atherosclerosis
+Cardiac related conditions which cause poor delivery of blood to various parts of the body
+Poor vascular health could be due to causes like narrow space within blood vessels (e.g. atherosclerosis), vitamin B12 deficiency, etc.
+Psychiatric conditions: Some men have the fear of performance (performance anxiety), which makes them believe that they cannot or do not get stimulated well enough. Although this is less common in men your age, it will still have to be ruled out sir
+Damage, injury, trauma: Can occur due to accidents, sometimes masturbation related accidents, etc.
+Chronic conditions: Diabetes is one very common example of this category which not only causes a direct impact on the libido of a male, but also affects the blood vessels which are a major contributing factor to the male libido
+Side effect of medications (e.g. finasteride)
+Spine related abnormalities: Many major nerves pass through the spine, and some major reflexes come from different parts of the spine. Any abnormalities in the spine (e.g. disc prolapse, bone spurs, etc.) can cause these nerves to dysfunction resulting in poor functioning and performance of their individual roles
and a few other causes

So the first step would be to gradually conducted an array of investigations to find the cause for your reduced sensitivity and address it. Once the cause is identified, trust me, half the battle is won

2. Difficulty in maintaining an erection: Although people place both loss of sensitivity and difficulty to maintain an erection in the same category, they are not to be confused. Many men can maintain a good erection, but still experience loss of sensitivity or reduced sensitivity due to which they find it difficult to ejaculate/climax.

This added symptom gives us a hint, pointing us towards the direction and understanding that the issue is not merely pathological but also has something to do with 'performance anxiety', at least partially.

So while the cause is being identified, I would also strongly recommend counselling to help you to regain your confidence.

The journey towards complete recovery may be long and time consuming, but once the cause is identified you can believe that your recovery is certain.

I hope you find my response helpful, and informative. Please forgive me if it was a tad bit too lengthy.

Please do not hesitate to write back to me for any further clarifications, I am always here to help.

Best wishes.

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