Why do you think that it is swollen? Were you to rough with it while cleaning, masturbating? Yes, you should see a doctor, but in the mean time soak in a hot tub of water for a few days, with some epsom salt in it. About 2 cups full. sounds like you have any infection of sorts. I've read that peroxide is also great for many things. You might try a cup of it in your bath water if the epsom salt doesn't help. Until you can find out whats up with your foreskin, be gentle with it, and continue to keep it clean.There are some over the counter creams at your local pharmacy for infections.
You could try a cream for yeast infection. This may be what you have. Guys get those just like the women, and I'm told what works for them works for us as well.