You'll get lots of advise on here but I'm not sure how much will be "Good Advise"!
You started out with about 4.5 inches of travel in your suspension.
You lowered the bike 2.0 inches so now you have 3.5 inches of travel.
You sit your 260 pound carcass on the bike and use another 1.5 - 2.0 inches of travel.
Now you add a passenger and,,,,,,,,,,,,,,,,well, you get the picture.
You can't fix it but you can make it so stiff that the suspension can't function resulting in driving your arse up between your shoulder blades every time you hit a bump.
You'll hear tons of arguments from guys with lowered bikes but in the real world, there is no fix. You pay a huge price in suspension performance when you lower your bike. Not to mention what you've done to your progressive linkage in the rear by changing the length of your dog bones.