Can't retract my foreskin, penis head is very sensitive

Okay so I have few concerns. 1st of all I cant always retract my skin. I can usually do it with a lot of help from the pre-cum when my head is very wet. It can work with wanter sometimes but not often and not as well. When I do retract it I cant get the skin back over the head (errect or soft) unless I pull the skin as far down as possible (usually as fat down as half way down the shaft) and then squize and pop it back over. Is that bad? How can I fix it? What should I do?

Also most of my headis very sensitive to the touch (especially a dry touch) it.irratates and kinda hurts to the touch the very tip does not but the most of the head does. During sex its not as bad but still hurts. Getting head feels both pleasant yet painful. Is that almething to worry about? How could I fix that? Shout I let it breath for few days and leave the foreskin retracted?

Another thing sometimes during masterbation a creamy lotion looking and feeling substance comes out of from under my foreskin. It smells bitter and it has just started to happen. What is that? Is it something to worry about? How should I treat it?

Last thing under my head thereis very white dry substance. Some is easy to whipe off but other is very dry and stuck to the skin. It kinda feels like a dryed paper towel and I cant whipe it off, I have to peal it off. I think that it may be "stigma" or something like that but im not sure. The stuff that can be whiped off kinda feels like a thick cream and thenstuff that needs to be pealed off kinda feels like dried up paper towel?  What in the world is that sh*t?! Is it natural? How do I clean it and get rid of it?? Im pretty sure that its not an std cause as far as I know all of my partners have been clean and none of them has brought up anything oddnormal after having intaractions with me.

Please help and answer these questions. Im lost and very worried.

I am 19years old and the white and the cremmy stuff started appearing in early 18s.