So there are a few possibilities that I can think of. That either her pellets or her hay is bad in some way, which could be potentially life threatening due to the organ damage it can cause. With hay it could be mold or something it's sprayed with(if this is a new batch to you when this started). With pellets they can go bad or something bad can get mixed in during the pelleting process. If it's her pellets/hay, then I would throw out the old stuff and get new stuff making sure there is nothing off about it(no musty or sour smell, no white or black spots, no white dust) and that the pellets are a completely different batch or brand from the last one.
The other possibility if it's not her food, is that she's contracted coccidiosis, which can also be immediately life threatening if not treated correctly and promptly. Which based on that tear shaped moist poop and the mucous you saw could be a very definite possibility. In which case, if it was me I would want to begin coccidiosis treatment right away, with either the antiparasitic ponazuril/toltrazuril or with a sulfa antibiotic like Albon(sulfadimethoxine) or sulfamethoxazole trimethoprim. Your vet may be able to do a fecal test to determine if it's coccidiosis or not.
http://www.medirabbit.com/EN/GI_diseases/Protozoal_diseases/Cocc_en.htm
http://wildpro.twycrosszoo.org/S/00dis/Parasitic/Coccidiosis_Hedgehog.htm