I have faced this problem for last few weeks. The tip of the vein shows irritation when I get a signal for urination. I am just entered into seventieth year of my age and I am on prostrate glad medication. 

Use of product like Lacto calamine soothes the same. Also it is OK after urination is completed. 

There is pink spot on the tip of the vein and the size could be 1 mm dia.