a nagging injury bug

i'm having some knee issues, and try as i might otherwise, it seems to have become a nagging bug. it's at the point where the soreness persists almost continuously. i'm not quite sure how this happened.

i haven't been engaged in any activity levels any higher than normal. in fact, my activity levels this year have actually been lower compared to the usual ironman training cycle, and i've actually only recently been returning to some base levels of fitness to resume the ironman training load i typically follow during the summer.

what's happened, however, is that i'm having soreness in the inside and outside left parts of my knee, in what feels like ligaments or tendons. i feel it when i'm extending the joint (i.e., bending it), particularly when i'm putting my weight on the knee--such as when i'm going up steps, rising from a kneeling position, doing a lunge, etc. 

i've tried to rest it, but just when i think it's gone it comes right back. it wouldn't bother me so much, except that 1) i've never felt anything like this before, 2) it seems to becoming chronic, and 3) we all know the magnitude of the risk associated w knee injuries, particularly ligament ones.

i've checked around on-line, but i haven't found anything that really helps me understand what's going on. the best i've seen so far is this:

http://www.webmd.com/fitness-exercise/guide/knee-ligament-injuries

and these videos:

outside knee pain: http://youtu.be/ULjca96n23o

and

inside knee pain: http://youtu.be/bO3_dJS5ywk

i know that at this point the solution is rest, but the question is how much? and is there anything i can do to prevent it in the future?

i notice that in the videos they mention a knee problem is usually indicative of issues above and below the knee, which is something consistent i've heard w all the physical therapists i've worked with in the past. particularly the point about weakness in the buttocks and lower back--this is something that my physical therapists have pointed out, and something i've been working on over the years. but i'm not sure if this is the source of what i'm experiencing now (like i said, i've not felt this type of soreness before).

i'm going to try these and see what happens:
injury prevention: http://youtu.be/znAZZJwYzcU

knee massage: http://youtu.be/qJQz3FlTUqg

still, i'm a little bummed, since i was just starting to ramp the training load. and i was just starting to get back to feeling like my usual self after several months of really bad and really inconsistent training. and it really sucks to see other people going hard while i feel like i'm limited to 50%. i'm hoping i don't have to go to the doctor, because that would really hurt the wallet right now.

let's hope this heals itself soon.