Anxiety can cause the feeling of something being in your throat. It's a psychosomatic symptom that is pretty common. I'm not a huge fan of wikipedia as a source, but this article is brief and descriptive:
You can do some more searching about it, even though you state that symptom is more or less resolved, I think it will help you have some peace of mind at just how many symptoms can be caused by anxiety.
As for your other symptoms, GI disturbances, such as nausea, diarrhea, appetite changes are one of the more commonly seen anxiety symptoms. You don't want to assume it's related without checking with your doc first, but most definitely if you struggle with anxiety, that could be the cause of your nausea.
Knee pain, not likely related to anxiety. Anxiety and depression can cause some aches and pains but something more specific like that is not likely to be caused by anxiety. I would recommend seeing your doctor about that.