Comet struggling to poo

[Zomby]

My comet [Shown in picture] is struggling to poo! She lies at the bottom of the tank, fins clamped and stays very still. Her anus is slightly swollen and she's only pooed a tiny bit! She used to be a poo machine! I've been told to feed her daphina and for the past week, she's pooed a wee bit of it out. I've tried peas the week before and same results. :( This is the first time it's happened in 3 years since I got her. PH and nitrate levels are fine, ammonia levels are also fine, she had a 60 litre tank to swim about in. I'm running out of ideas on what to do!

[DrNic]

It might be worth adding some anti-bacteria/fungal meds to the tank. The failure to poo might be the result of some kind of infection.

[Zomby]

I've got internal bacteria and single cell skin parasite meds. Should I use the internal one cause she doesn't seem to show any signs of skin infection?

[rageybug]

What has the AC World come to when we are posting about poop....