I get this pain in my right knee when i run what do u think it is? when i run for a while it starts to hurt so that i can't even walk on it but after a while it will go away

Do : Do you have any locking, popping, grinding, giving way or recurrent swelling? If it is just pain i believe the most common problem would be patellofemoral pain, that is coming from your kneecap. Another possibility is an iliotibial band syndrome.

IT band.: It could be your ilio-tibial band, if the pain is on the outside of your knee. It is typical for it to start hurting, after you've been running for a while. See a non-surgical sports medicine specialist to see if it is it band or something else.