I got into running this year, at first everything was going fine and I went from doing 3-4 km runs to 13 kms going up about a km each week.
Now I can't go longer than about 3-5 kms without getting painful knees , or once I get to around the 3 km mark I'll need to stop for about a minute because of the pain and then run again for half a km or so before the comes back. I get a lot of knee swelling. After the run the pain isn't too bad, it's mainly there while I run.
The following days there's not much pain but a little bit when I bend them.
I have also changed shoes, focused more on warming up, taken 2 weeks off.
Any idea what my problem might be?