Over the last 2 months or so of doing heavy squats (200 lbs - 262 lbs) I've frequently had pain in my knees. During the last 2 weeks, it's been especially persistent and seems to be mostly in my left knee. I'm normally sore after working out, especially in my legs and lower back, but the knee pain seems to persist long after the other pains go away.
What does it feel like? Well, it's on the front side of the leg, centered just below the knee cap. By "below" I mean "in the direction of my foot", not "closer to the bone". It's hard to describe the sensation exactly. It's kind of a pulling/burning feeling. It feels somewhat different than muscle soreness elsewhere, but I don't feel like anything's grinding or scraping or popping. It's not a "sharp" pain.
As far as intensity goes, it's not excruciating. Actually it's mild enough that I feel that I could ignore it when doing my squats and continue performing my workouts as planned. I'm just not sure that's a good idea. It is bad enough though that running for more than a minutes or so is a very unpleasant idea.
I do not feel any pain when standing, sitting, or walking. I do feel it whenever I ascend/descend at all. Getting up from a chair, walking up or down a flight of stairs, and of course when doing squats. I also feel it when running.
I've tried skipping a couple workouts, and although the pain seems to gradually get better with time, 5-6 days is not enough to get rid of it, and it comes right back when I resume my workouts. I had been more or less ignoring it for the last month or so, but since it's now preventing me from running, I'm getting more concerned.
I have also tried using a foam roller on the muscles surrounding my knee (but avoiding the knee itself). This seemed to help with some other pains/soreness I'd had, but not with the knee pain.
I'm 95% sure the pain is caused by my squatting. It always gets worse during/after I squat. I squat just below parallel, with a shoulder-width stance and my feet pointing outwards about 15 degrees. I try to keep my knees following that 15 degree direction, pointing in the direction of my feet, when I descend. Historically I've done 5 sets of 5 reps, but more recently I've been doing 3 sets of 5. I rest about 5 minutes in between sets.
So, should I be concerned about this, if so how should I handle it? Is it likely that I'm doing something wrong? Should I take a couple weeks off from squatting and running? Ignore it and keep going? Deload significantly and work back up so my body adapts more? See a doctor? I know you are (probably) not a doctor and not qualified to give medical advice. I'm just hoping to find out if this (1) ignorable, (2) a concern, but something that can be solved with a period of rest and/or dealoading or (3) a big problem I'll need professional help with.
Update: I saw an osteopathic doctor yesterday. He told me my tendons and ligaments were fine. In fact he said "your ligaments look like they're built to take a lot of punishment!". He diagnosed patellofemoral pain syndrome AKA "runners knee". He told me the inside of my knee cap had become rough. He prescribed R.I.C.E (Rest, Ice, Compression, Elevation) as well as a twice-daily stretching regimen, and weighted leg extensions 3 times a week. He also suggested I take ibuprofin, especially if I'm doing anything to aggravate my knees. He told me recovery could take 6 weeks or more, but call him if I didn't see a significant difference by the end of the month.
So at this point I'm going to follow the routine the doctor gave me for the next 6 weeks or so, and avoid squats, deadlifts, and running. I will continue doing the other exercises I'd been doing (bench press, overhead press, rows, and pull-ups). I may also try swimming if I feel like doing cardio (but I'm a terrible swimmer). After I feel I've recovered I'll start squats with about 50% of the weight I was last doing (262 lbs was my peak work weight) and I'll work my way back up. I'll have someone check my form then too.
Thanks for the answers. They helped me to realize that this wasn't something I should ignore, and that my squat form was likely at fault. I'm marking Dave's answer as "most helpful" for the strong suggestion to see a doctor, which I did. But I also really appreciate Berin Loritsch's answer for the form tips and the TUBOW suggestion especially.