Not sure of your age but you mention grandchildren. Sadly, knees take a lot of wear and tear over time and it could be any number of things. Most are not going to heal on their own. My son's dog jerked me sideways when he ran after a squirrel and I had surgery to repair a miniscus tear, luckily for me, not too serious. My knee still aches occasionally. Better to get checked than to string it along and it only gets worse. My insurance wouldn't permit an MRI initially and I had to try cortizone injections and other treatments first. I hope your insurance doesn't string you along.