Don't raise the lights......you're using flouros right? Just grab a good paper towel and go around pulling leaves apart and dabbing up the moisture. When you see two leaves overlap that is usually where water forms. If you raise your flouros too high they will become useless to you. I honestly believe your issue was water or nutes splashed onto the leaves and ANY light will burn wet leaves. Dry yours.

IF you are running straight DWC I'm not surprised that the lower leaves are dying off. As long as your new growth looks good and it's just the older LOWER stuff I personally consider that normal. If the drooping starts crawling up your plant and appearing in the newer, higher growth I would call it a different issue.

As for humidity.....all you can do is your best but if it remains high you may very likely encounter disease issues later. Consider a good fungicide like Serenade and follow the directions on the bottle EXACTLY......anything you can do to prevent your molds and funguses is good.

Your welcome. Hope that info helps.