Lingering knee injury won't fully heal?

I hurt my knee about 6 weeks ago by falling (repeatedly) on an ice rink with no knee protection. The knee was swollen for a week or so then subsided but I could barely bend it without extreme pain for 2 weeks.

Currently, walking is difficult and it is near impossible to tie my shoe. Sideways movements hurt as well, for example if i were to rest my ankle on my opposite thigh. What I can do? How long should I wait before seeing a doctor?

The specific location is just south of my kneecap.