Could Pain In Knee Be Due To Irregular Workouts?

I have suddenly developed knee pain, my i.t. band I believe. I am very active and I have not been consistent on work outs. I usually work out 4 to 5 times a week. My Mom passed and have been busy with that stuff. I walked 2 miles on treadmill (trying to do some sort of workout) and felt fine, Then I did my yoga stretches, (pidgeon) foam rolled and seemed to be fine, Then about 2 hours later I was limping. It doesn t hurt when I sit, but walking is painful. I took tylenol last night and wrapped it and now I have it elevated with ice wrap.