The solution is not always add more food, unless you're using something like fish fertilizer don't always jump to this first. What is your air flow situation? This time of year it's still pretty hot so mid day temps can soar. All of the above problems happen from lack of air flow. Waterlogging isn't a problem if there is moving air to keep fungi back. Darkness + high humidity + no breeze = mold. Easy enough. Add a fan, watch your new growth, old leaves this damaged will be shed so they're no indication of plant health.