Well, this sounds like a classic case of Peyronie’s disease, a bend of the penis shaft which is usually much more noticeable when erect. It’s usually not terribly harmful, but obviously it’s disconcerting to the ‘owner’. It often happens after some trauma to the penis - for example, vigorous sex or masturbation, but apparently it can sometimes occur without any known incident. Do you recall any type of trauma - a blow or vigorous sex or anything like that?
The one thing that can be a little concerning is, it sometimes gets worse over time. What happens is ‘plaque’ formation in the tissues on one side of the penis, in the corpus cavernosum, which is the sponge-like tissue that engorges with blood to cause an erection. That area of plaque is harder & won’t expand as much. So for example if you have such an area on the right side, the left side will expand more, causing a curve to the right. Most guys have some slight ‘bend’ in their erection, not many have one that’s perfectly straight, and a slight bend won’t affect your ability to have penetrative sex. Obviously if the bend is or becomes more severe, it could cause problems.
There are some treatments that may help reduce the bend. One is acoustic shockwave therapy that can break up this plaque & is also used to restore sexual function to guys with ED. However, it’s quite expensive & not covered by insurance. There are also a couple of ‘home use’ devices that use acoustic wave therapy to break up plaque & help restore function, they’re a bit pricey, but cheaper than the in-office treatments. Some have claimed applying Vit E creme to the area may help reduce the bend, but solid proof of this is lacking. You can get a lot of information by looking up Peyronie’s disease and treatments for it online.
You might want to consult a Urologist & see if you can get any add’l info after an exam.
Good luck with this issue & check back in here & let us know what’s found & if you’re able to find a solution..