Simplest easiest soft tissue work for you to do is probably self myofascial release (foam rolling/tennis ball rolling, etc.).
Hows tightness of inner/outer thighs, hip flexors, lower legs? Usually if squats are giving a client pain in their knees, its because there's some kind of flexibility/strength imbalance and their knees aren't tracking correctly or they're not keeping their heels down.
Another thing to consider is footwear.
Also could be simple diet/training induced inflammation.
Vid would help! Good luck.