Hard spot inside my penis

Hi guys I have noticed some difference on my penis, about 4 centimeters from the base on the inner vein a have a hard spot I don’t know if its vein or something else, but it is some string with bulge when I jelq it got harder and I think when I stopped for a day it disappear but when I start over It appear again. Its not painful but its weird.

Thanks for your opinion, what should I do.