Your exported file needs to be under 0db. No clipping. Otherwise go back to the multi track and re mix.
Use Solo to find the offending track.
Look for the tracks peak and hold meter showing red.
You can try the LP 64 multi band on your master buss. Make sure to set the attack fast.
The multi band will only compress the offending frequency not the whole song.
You can fix stereo files in a wave editor by zooming in on the overs and applying gain reduction. But that takes a long time if there are a lot of them. I only do that on one shot live recordings. Wave editors let you edit left or right or both.