Noise from the back end

Took my rzr out for the first time this weekend to renegade ridge. After a couple hours of riding I started hearing a whistling or humming noise from what I would assume the belt. Then when I would be weaving through trees I would get a clunking noise from the back-end as well. I’m not familiar with rzrs yet so I don’t know the normal noises from the bad ones. Any info would help