It sounds as though you may have some lymphangitis which is causing the skin to inflame (get puffy) especially around the corona of your penis. It's quite possible you are being too aggressive with your masturbation or too frequent. The penis is not a steel rod, actually it is exceptionally delicate, and if you abuse it by not using lubrication, or simply handle it too much/often, it will get irritated.
I don't know exactly what you mean by sticky, because it doesn't sound like you're describing a fluid or waxy substance, more of a sensation. This kind of adhesion sensation can be internal, especially if the skin is inflamed, and what you'd be feeling there is the tugging of the over-inflated skin from its attachments.
Unfortunately, if this is the case, the only solution is to refrain from all handling and use of your penis for anything other than the necessary urination. It can take 2-3 months to resolve this kind of inflammatory issue because the lymph channels do not have a pump and take a while to settle down. Any further irritation just causes more inflammatory response and longer time to heal.
You didn't mention any kind of allergies, so it is assumed you don't have a mild latex allergy or some allergy to a new detergent in your clothes, or some soap from bathing.
If you do have a discharge from the skin, you should actually see a doctor. It's not safe to use some OTC medications used for skin infections on your genitals, and only appropriate to use the right ones for an actual condition, not guessing.
Regardless, the point here is that your penis is delicate, and when you mistreat it, you will cause yourself an injury which will take considerable time to heal.
As far as weight gain, belly fat shortens your apparent penis length by about an inch per 30 pounds, however this does not cause you to "create" foreskin. It only refers to the distance between your skin surface and your pubic bone where your penis anchors.