Looks more like inflammation from the stuck poop. If you've been able to keep the poop cleaned off, it should be back to normal now. If not and/or there is white pus, then vet right away. The soft poop is usually from the baby starting to eat too many pellets, from the carbs in the pellets disrupting the microflora in the GI tract too quickly. If more good quality grass hay(no mold, no noxious weeds, low dust) consumption is encouraged and less pellets, that should balance the gut and stop the mushy poop.
https://rabbit.org/vet-listings/
Rabbit syphilis is usually indicated by lesions, crustiness, and/or bumps forming around the genitals, eyes, nose, and/or mouth.
http://www.medirabbit.com/EN/Skin_diseases/Bacterial/Syph_gen.html (rabbit syphilis)