@ this point am thinking lack of calcium, aquatic frogs especially young require good calcium but answer below please.
OK to me she looks seriously under fed for a female how old is she?, please post back first the water paramiters! If you unsure take small sample to aquatic store(post back PH then ammonia nitrate nitrite levels, secondly what and how much are you feeding them?(post entire weeks feed) Lastly post your full cleaning regime including how much water you change frequency and do you hoover gravel and wrinse out filter sponge regular, also what water conditioners used