A good start is to get it weighed, total weight, right and left side and while your at it , front and rear axle . This is good information to have for all kinds of reasons. A lot of people overload their RV's and don't even know it. Sometimes you start off light and little by little add weight and don't think that it all adds up. It's just good to know where you are . If that all appears to be ok then a number of different things could come into play regarding your suspension . A qualified RV Service shop would have to help you locate your problem most likely.