African Clawed Frog is ill

[Kethate]

I noticed a subcutaneous formation on my pet's side. Has anyone encountered this?
What's it? Is it dangerous? After feeding, it becomes more noticeable.
The frog is 13 years old.

Tank 30L, temperature 23 C, water replacement is made with standing water (more than a day). There is no filter. We change the water every two to three weeks. We feed them with bloodworms, never gave vitamins. The size of the frog is about 7 cm.

[BossFrog]

may be a tumor or some other growth, may be impaction since it’s more noticeable after feeding. both could be intensified by the (quite impressive) age of the frog. i would see a vet if possible. what are the condition of his stools?