Hello,
I realized this spot while masturbating yesterday. I'm pretty sure that it wasn't there before. All I did differently than my usual routine was putting some petroleum jelly on the area before 2 days I spotted this. I don't even know if it is related. No pain or anything when I touch, and I've never had sex before. What can this be?

What you most likely have if you are not sexually active is the petroleum jelly has blocked a pore, or even skin follicle (they are still there even though you cannot see them and they don’t grow hairs). My first instinct was that you have done something different to what you usually do …
So, you need to look to 2 things: i.) if you can get a hold of some liquid Antiseptic and carefully dab a very small amount on general area 2 or 3 times a day (if you live in the UK get some TCP) - do not use an antiseptic cream or ointment as this may make it worse. These (I can see potentially you have more than 1) should begin to fade out quite quickly with the liquid antiseptic, certainly after 3 or 4 days - particularly if you take a break from masturbation during this time. I can’t make out whether you are circumcised - my guess is not - so you need to be aware that issues like this crop up because of an interaction between what you have applied (as a Lube for instance) to your penis and a friction reaction that is going on during masturbation. Obviously, the longer period of time you masturbate for, and the frequency in which you masturbate within, say a 48 hour period means that there is a greater amount of friction and less time for the natural skin healing / replacement process to take place - then there are the Lubes to cope with on top of this process of skin renewal and repair.
ii.) Look to getting a reliable Lube if you were not happy with what you previously used - so, water based Lubes are okay, but they often dry-out quickly and don’t feel very nice on the skin. A pure plant extract such as Coconut Oil or Aloe Vera Gel may be the things to try in future - both of these have natural skin healing properties too. Try each for at least 3 or 4 weeks, then choose the one that suits best …