I got a flu shot a week ago which left a red circle and a knot on my arm. we tried ice but it didnt help.

See your doctor: Make sure you don' have thrombophlebitis or another problem altogether, where the flu shot may have been injected creating a clot, in which the clot just needs to be removed by a doctor, not you. Or it could be something else. The best way is to see your doctor, and get it checked out. One week is a long time for a problem for a flu shot to persist. If it's just a bruise, that will go away in time

Flu shot reaction: You are experiencing a local reaction to the flu shot. It will likely resolve over a short amount of time without any lasting effects. The shot is basically a foreign protein injected into our bodies. Our bodies produce antibodies against that protein but sometimes create local soreness and reactions - like redness of the skin. Try some benadryl cream and avoid rubbing the area