it sounds like your wheel is out of true. It happens. You can either learn to true it yourself by tightening various spokes where the woop is, or you can take it to a lbs and have them do it. If you end up trying to fix it by yourself, watch some videos and read about truing wheels first. You can do more harm than good if you just jump in there are start turning things, but there is only one way to learn. Good luck!