I have been training for almost 2 years and have added in some cardio in the last year (running, combination of sprints and liss). I usually do both AND squat AND deadlift (albeit i dont go heavy every time) in the same session 2-4 times per week and i only just recently started getting knee pain but only when i preform basically anything resembling a hamstring curl, they feel fine going up the stairs running and deadlifting but my squat has started hurting just a little bit.
I suspect im just doing too much to my knee joint too frequently and i never keep my knees behind my toes during squats (never thought that made much difference except making it more difficult). One thing to note is that i can only afford a membership at planet shitness (which has no free barbells) so all my squats and deadlifts are on the smith machine which blows but could that be whats affecting my knee, or just too much volume? Any tips for recovery?