Question: Can a lone fire belly be gravid?

Hello kind newt experts! I am hoping you can help solve a mystery for me.

I have a 14-year-old female (?) Japanese Firebelly who has always lived alone.

My newt goes through cycles every couple of years of getting fat vs. bloated vs. gravid. This involves only the abdomen and cloaca. The neck, head, and limbs have never been swollen. The newt does not seem uncomfortable, but the belly gets so swollen her legs can't touch the ground if she is trying to walk. She does fine swimming, climbing, and lounging in the water. She always remains active and vigorous, and acts ravenous during these episodes. The belly eventally goes back to normal over a few months. I have never seen anything that looks like eggs.

I am trying to figure out if a lone newt could be gravid and just resorbing eggs, or if this is something related to the water/environment? I would think the newt would not have survived 14 years if it were illness.

I am including a picture of the swollen newt, and one of her more typical svelte form.

I would appreciate any advice or thoughts!

I think that in some cases, they do gain weight in preparation for breeding season.

If it happens consistently and at similar times of the year, then in all likelihood it´s just that she is becoming gravid and then reabsorving the eggs. Perfectly normal. She may even lay unfertilized eggs on occasion.

On a different subject, you should really revise the housing conditions of your animal, from what can be seen in the pictures it looks like the conditions could be hugely improved.
Check this article for starters:
Caudata Culture Species Entry - Cynops pyrrhogaster - Japanese firebelly