Penile chafing is actually a fairly common problem. It can happen if a guy is having sex frequently, or even from doing – ehem, his own pleasure seeking a bit too often, or it can just happen like it happens to skin anywhere else on the body, from irritation or sensitivity.
It can also happen from various sexual lubricants that are used, for example I believe one of the ones that leads to this if it is overused, especially in guys with sensitive penis skin, is the warming sexual liquids, like KY warming and other similar ones that either have cinnamon and other skin irritants in them, or contain ingredients that warm when they are rubbed or touched.
Those are typicallly used as female sexual enhancement rubs, but they often come in contact with the penis upon penetration and the friction combined with the heating can irritate some guy’s skin. That’s just my opinion though, there’s really no published research on that or anything (and why would there be).
What you need to do if you’ve rubbed the skin raw on the penis is, first of all, take a breather from sexual activity until the chafed spot is healed. This can be tough, but believe me, it can be painful if it starts getting rubbed so much that it gets raw and starts to bleed or otherwise ooze other liquid out of it. When it gets to that stage, it requires an even longer healing process, so you want to try to avoid that stage all together if possible.
Now, as far as what you can do, you will need to take care of the chafing on your penis by putting some sort of soothing ointment on it, you can even use one with antibiotics in it like Neosporin or other similar anitbiotic ointments to prevent it getting infected. There are some homeopathic ointments that may also be used, but it’s difficul to say what may irritate some guys more and what may work as an ample soother. Aloe may work on some guys but may irritate others.
My preference is to just stick to a light layer of Neosporin, so that it keeps the wound moist and doesn’t allow it to just peel and get raw again. Also the anitbiotic action will prevent any sort of infection which is an added benefit, and may even help speed the healing process.