What Causes Build Up Of Lymphatic Fluid Below The Head Of Penis?

In 2011 i first seen a fluid bubble below the head of penis after masturbation and it always goes away after some time but when i got erection and after the erection i appears again ,, and i searched on web and found that it will be lymphatic fluid build up. And i mainly appear when i wake up in morning and after long erection or after sex. This bubble is half inch long and little wide . It present top of the shaft and below the head of penis on left side I want to know is there any permanent cure of this problem. And in other queries i have seen doctor recommended to avoid sex/ masturbation for some weeks for permanent cure but in night i got erection so how to avoid this. Sir/madam please tell me the permanent cure of this problem