It's smegma. Smegma is a natural lubricant and cleanser that forms on the head of the penis and the head of the clitoris. In our parents' day, smegma had a bad reputation and was thought of as a horrible sign of an unhygienic lifestyle, however we now know that it's actually nature's cleaner and protection. Your penis is meant to be moist like women's privates, but most Americans are so used to circumcision that a callused, sometimes hairy, dry penis is "normal" to them. Ew- lol!
If smegma is allowed to rest for too long, the bacteria it traps may overgrow. You can wash it off, but sometimes just wipe if off so that you don't get rid of it fully. If the smell bothers you, simple vegetable oil eliminates odor and helps hold moisture in.
By the way, please work through your embarrassment. Doctors have seem much, much, much worse things than smegma and that's just during their training! There are actual PROBLEMS that you may face in the future and it would be greatly beneficial to you to not hesitate to see a doctor.