I have chest pains while riding a bike. should i be worried i'm riding it now and when i stop it gets kinda better?

Unlikely: It is unlikely that a 20 year old woman able to ride a bicycle has chest pains from a cardiac issue but not impossible. If the discomfort continues you should seek medical attention. It is most likely musical skeletal but an EKG would help to define the problem.

Probably nothing: This could be a lot of things. Need to know if there is a family history of premature cardiac disease but because of your age this could be something as simple as reflux