Hourglass Shaped Penis/ Ed???

I used to have normal erections, but for about the past 2 years I have this problem that is getting worse and worse! When my penis is attempting to get an erection and it is filling up with blood, my penis gets an hourglass shape "temporarily" until the rest of the penis swells up like normal. As this happens it is usually somewhat painful and my urethra near the tip of the penis hurts. But then it stops after the erection is formed like normal. In other words, the base of my penis begins to swell up as im getting an erection , and the upper part of my penis (just below the head of my penis) begins to swell up, but the middle part of my penis is indented, squeezed in and constricted! It looks just like an invisible band is squeezing the middle of my penis giving my penis an hourglass shape. But as the penis continues to fill with blood it eventually swells up like the rest of my penis. From that moment on my penis looks normal, the hourglass shape is only temporary.
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I did not have this my whole life, it just started about 2 years ago. I have not damaged it that i'm aware of. This is horrible and I do not think that it's peyronies disease cuz I do not feel any hard lumps in it. I'm only 29 so i'm not old. I have no diseases that I know of.