Running on hold

My left knee seems to be aggravated again and swelling. No pain, just somewhat swollen.
I have not run since last Wed. The orthopedist states no running while swollen. It is feeling better and not as swollen. Will do some cross training tonight and maybe a run tomorrow is it remains good through cross training.
I get frustrated when it gets like this but I just need to be patient and rest it. If I consider the years of roughing my knees up with softball and volleyball, I am grateful to run at this point.