Sounds a lot like a meniscal tear. Be VERY careful trying to self treat by pushing your patella around. If you have insurance (or even if you don't) it is HIGHLY advisable that you have an orthopedic specialist check you out. Bad news is, if they think it is a tear in the knee you are going to have to get an MRI which can be pricey. Don't delay though. If it is a tear and you catch it early you are more likely to avoid surgery. If you dink around and keep training on a tear you are not only destined for surgery but you also increase the likelihood of a less successful outcome. These are you knees not a finger so take the warning (from your body and from me) seriously and get a checkup.

BTW, a good ortho knee specialist in a facility that also caters to sports med is the way to go. They are often more likely to take into account your desired sport/activity level and other related concerns should surgery be required.