Penis question. Penis is too tight below my penis head.?

i am an uncircumcised 17 yr old male and my penis is size is being limited by the tightness of the skin just below my penis head, it's like my penis is much quicker but my skin wont allow it and it tightens to a point that when i masturbate the skin below my penis glans would tighten over my penis head causing it to deflate and after that i would be semi hard and never full hard. i dont know what to do, or what it is, my penis girth in that area below the penis head is nearly an inch smaller and i think that's the reason as its much tighter in that one area than it is in the thicker areas of my penis which doesn't make much sense. Thanks for any answers. if you need more information i will include it when mentioned. Thank you.