knee injury concerns

[s0586958]

I ran a half marathon (first time running more than 4-5 miles) nearly 8 weeks ago and hurt my knee. Around mile 9 my knee started to feel uncomfortable and by the time I was finished I could barely walk (like 7-8 on a pain scale to 10). For a day or two I couldn't bend my knee much at all without feeling pain and it took about a week before I could comfortably walk again. The pain came from my right knee, just right of my knee cap and slightly down as is toward my shin not my thigh.

I never saw a doctor so I'm not sure exactly what I hurt, and I figured the usual RICE would work and kept away from using my knee. After like 2 weeks the pain went completely away. It's now 2 months since this happened and I've tried running again a few times recently but my knee starts to feel uncomfortable pretty quick. I've done the bike and weight training with that knee (squats, lunges, etc.) since and felt no pain at all.

1) Should I be concerned that this is still an issue after 2 months or am I being paranoid and should just give it more time?

2) Any suggestions for rehab/training exercises that might help?