Is it possible for the penis to pull inward/shrink? is there anything that can cause this? anything to reverse this? have you ever heard of this? treatment?

Both the penis & testicles do get smaller as you age. Avoid smoking or excessive alcohol intake. Exercise. Get erections regularly. If you still have concerns, consult a urologist for evaluation & advice.

Penis does not pull inward or shrink unless its blood supply is cut off. Often a flaccid penis is misinterpreted as to its size. If you have normal erections there is nothing wrong . if still in doubt see a Urologist