I am a 17 year old male, and I've been experiencing problems with erections recently. While getting an erection only the lower half of my penis will get erect/hard, whereas the rest of the penis stays soft, from the other half until the head. I don't know what may have been the cause of this, the change was overnight.

I've been searching about this kind of problem but found nothing. Anyone got any information about the matter? Thanks in advance.