One Strange Spot Under Glans (urgent Help!!!)

I'm getting worried about this now, i've looked all over the internet and can't find a single thing about this.

Just under the glans, when I pull my foreskin back, there is a strange spot/lesion on the left hand side. It's only visible when my foreskin is pulled back, and even then it varies from visibility. Sometimes it's very visible, other times it's hard to see. It seems to become more visible when I am sexually active (with masturbation).

It provides a strange, yet sometimes pleasurable, sensation in my penis. However, due to not being able to find anything about it, the fact that it's tender, the fact that it sometimes looks like there's some sort of pus inside (although I can't get it out) and that I did pull some pus-type substance out of it a while back is getting me a little worried.

It's soft, and is textured much like a popped blister, when the skin is soft. Anyone have any ideas about this? Any help would be so very greatly appreciated.

I'm 18, and am a virgin. I haven't been sexually active (aside from masturbation).

Thank you in advance.