Big pimple problem

good evening, for some time, I have this pimple at the level of the penis, it is transparent (color of my skin) and when I touch it it is a little soft and when I pierced it with a needle, l water came out (then a little blood) but it came back after a while! what do you think? it’s serious ? some advised me a cream based on Arnika
Can you please help me ? Thanks,

This sounds most like a Penile Lymphocele - these normally appear on the shaft of the penis. They are most often linked to pressure within the penis and are most often caused by masturbation / and / or sex.
Unfortunately they fade away in their own time but usually take a matter of days or weeks.
if the skin becomes broken again use a very small amount of undiluted liquid antiseptic after you have fully washed and dried the area