Constipation

Every few months my cat spends a few hours walking hunched over (as if trying to poop), meowing distressfully, and going to the litter box with nothing coming out. My vet has told me that it is just constipation and to make sure she is getting her liquids and taking probiotics. Other than meowing, she doesn’t appear to be in any pain or have any other signs on illness (still eating, drinking, and grooming; body relaxed; still jumping onto her cat tree). Last time she was doing this, she vomited while trying to go in the litter box. I also noticed very watery liquid coming out of her butt that has a very unique smell (the vomit smelled the same — it’s almost sweet?). Just trying to get second opinions on what this could be and whether it’s more serious than infrequent constipation. She also never coughs up hair balls, so I wonder if hair could cause this constipation.

Hello!  You consistently talk about feaces rather than urine here, but it is worth pointing out that if a cat strains to urinate then it can be an absolute emergency.  At the moment, it sounds as though your cat is urinating well (? - please check) but has vomiting and diarrhoea.  Fluid loss in this way can also become urgent, so please be aware that you may still need to call the emergency vet, for e.g. pain relief or fluids.  Emergency vets will help you to triage cases over the phone if need be.

Triage is the act of taking a history, perhaps over the phone and prioritizing in terms of urgency.  Phone triage sounds to be a good idea for your cat.