I am about 2 months into SS. Prior to SS I was doing a random exercises, one of which was weighted lunges. I started getting patellar soreness in my left knee because of poor form during the lunges, so I stopped doing them. Then I started doing SS so I never went back to the lunges. I've been foam rolling my entire quad, ITB, and hamstrings before each workout and I haven't had any issues in any part of my leg/knee since starting strength.
As I said I am about 2 months into SS. Two days ago I squatted 180 with no problem. Today I moved up to 185. In the first set, during 3rd rep, coming out of bottom of the squat, I leaned forward a bit and felt pain in left knee and some sort of inaudible, light pop/crack. I finished the 4th and 5th rep without pop, but felt more pain. (I should have stopped before the 4th rep in hindsight). The pain went away during the rest period and I massaged my knee a bit and things seemed fine, but then when I tested bending my knee with no weight, I felt a sharp pain (worse than during the squat). Of course, I skipped rest of the squat sets, and have avoided bending my knee in the hours since. I've also been icing my knee as well. Now I can bend my knee and there isn't pain, but I'm still being gentle with it.
So my question is, what should I do going forward. Based on my description above, I guess it's safe to say it was caused by my shifting my weight forward coming out of the bottom of the squat and putting too much stress on the knee?
I'm guessing there shouldn't be long term damage? Should an ice pack tonight, and walking around gently for the next few days be enough to have it heal?
How long should I wait before squatting again? And when I do try to squat again, what weight should I do?
Don't get off of it entirely. You'll want to keep moving the joint and doing some light exercises/stretches to keep the blood flowing to the area.
I'd try to squat again at your next workout, just listen to your body. Start with the bar and add as much weight as you can without feeling any pain. Start back from that weight and focus hard on your form so it doesn't happen again!
It makes me nervous that shifting my weight forward just a bit like that could cause an injury. Is there anything I can do to strength/heal the knee to guard against this happening again?
It could have been a freak thing, don't let it psyche you out.
I don't know of any way to specifically strengthen that knee other than doing single leg work, but that's not usually all that recommended around here. Most would just say to continue squatting with the best form possible and try to avoid what happened last time.
Sounds like you might have relaxed your back or hamstrings in the hole if the weight shifted forwards.