Hi VanBasten,
For pains located under the patella (Not patella tendinitis) due to patella maltracking I find a multi-faceted approach is best. Ice is great and you should continue doing this. Foam rolling around the knee is effective especially over the iliotibial band. Considering the amount of pain you are in you may require a course of anti-inflammatories, a visit to a physiotherapist to be shown McConnell taping for your knee and maybe some deep tissue massage of the lateral knee structures.
This advice is valid for patellofemoral pain and is not suitable if you have meniscal or ligament damage. The above techniques can be useful for patella tendinitis.
Hope this helps.
Here is a link to a information sheet on knee pain.
http://www.fountaingatephysio.com.au...ral%20Pain.pdf