Thanks to everyone for all of your advice and for the encouragement.

I haven't tried another spinning class YET, but I have been back on the treadmill and the regular exercise bike at the gym. I am hoping to try spining again this weekend.

Since I don't usually bike while standing I'm not sure I even know how to

Should I be rocking up and down/sort of side to side over the bike or should I try to hold my upper body still and more or less "run in place"? Or doesn't it matter?