Whenever I run it always seems to hurt just under my knees?

Could be Osgood-Schlatter disease. No big deal. hurts like crazy, but you grow out of it. Go see a doctor, wear knee bands under your knee cap and that will help.

I have had knee problems for years. so I know pain just tell her you need to have your knees checked that they hurt and just to be safe and make sure no real problem .I was told weight and normal routine wears away the cushion between the bones and joints.and starts arthritis

sometimes the stuff that is in between your knee bones (not sure what it is called) is rubbed back and forth so much that it starts to wear off and it goes to the point to were those two bones touch and they start to rub together and it is wearing down your knee bones... in other words your bones are scrapping against each other!!! my mom has the same thing!

there are tons of answers to this,

it could either be just

overusage

tendinitus

a sised

or maybe even (what i had in both knees) (but imm a dancer)

-- bilateral patella maltracting

i have the same problem, you probably have something called osgood slaters disease, its very common and usually not serious just annoying. look it up on the internet and see if that's it.