What Causes Discomfort In The Tip Of The Penis?

i am having this odd feeling in the tip of my penis, there is no pain, no swelling, nothing like that at all, what it feels like most is that there is something in my urethra towards the tip, and its been like this for two days. there is no sort of discharge or anything though, so i just want to know if this is something that is normal or should i go to a doctor?