My sister owns a western clawed frog who recently developed a large lump on one side of his stomach. He lives in 10 gallon tank with no gravel, except for a few small pieces that were left over when we removed it all. In the past, it seemed like he swallowed and passed a rock, but this time there are no rocks big enough to have made this lump. He is also severely malnourished, my sister feeds him little frog pellets, thought we also try to feed him beef heart as often as possible. Is this some type of frog illness? Or a symptom of being underfed? I will post a picture later.