A friend has severe pain and hard lump below lower left ribs; a ct scan and blood work in the er were negative. could it still be a hernia? what else?

Hernia Doubtful: Cts are pretty reliable for identifying abdominal wall hernias (less so, in the groin); this fact along w/the location of the lump make a hernia very unlikely. In fact, a normal ct should be very reassuring for "ruling-out" anything too serious. I have seen muscle spasms of the abdominal wall cause similar symptoms but that's a stretch w/o a formal exam. Your friend should follow-up w/their dr.