Hard to tell what's going on without you cleaning her up, washing the vent and the yellow material away.
She may be prolapsed, could be frozen poop/egg material and/or injury from vent picking.
Is there a way you can bring her in to wash up her bottom, take some photos. Blow dry her well.
General care is to apply an oil/ointment, triple antibiotic ointment, honey, sugar pack, anti-inflammatory cream, etc. to the tissue of the vent. If it's prolapsed, then it needs to be kept moist.
She may be prolapsed, could be frozen poop/egg material and/or injury from vent picking.
Is there a way you can bring her in to wash up her bottom, take some photos. Blow dry her well.
General care is to apply an oil/ointment, triple antibiotic ointment, honey, sugar pack, anti-inflammatory cream, etc. to the tissue of the vent. If it's prolapsed, then it needs to be kept moist.