I'm currently rehabbing my leg; I have a number of things wrong with it due to overusing it, not enough stretching, and weak glute muscles. Ultimately, everything impacted my knee and I was in a lot of pain. I recommend going to a physical therapist after you talk to your doctor. They can work with you on relieving the pain and then strengthening exercises to work on whatever imbalance is causing your knee pain.
Personally I've found that RICE does not work for me. Yes, rest is good but not to the point of being inactive. My knee acts up if I don't move throughout the day. So I'd suggest "G" instead of "R" - for Gentle activity. Ice increases the pain for me; whereas heat alleviates my pain. I was doing compression, but anything against my IT band worsened the pain so now - no compression for me. But I do wear a small knee strap.
I've started getting back to a regular workout routine and some days I over do it. At night, trying to sleep, the pain is the worse. Here's a routine I've been following the past week or so:
- gentle yoga/stretching
- foam rolling my entire leg, gently around the knee
- soak in a hot bath with Epsom salts, and a few drops of rosemary essential oil
- massage my leg with a blend of sesame oil and a drop or two of rosemary oil (sesame oil is said to be warming; rosemary essential oil is said to reduce muscle pain and joint inflammation)
- ibuprofen (I can only take it at night, it makes me sleepy)
That's been working for me. Good luck! Try to see a professional as soon as possible.