Slight 'give' in rear scute? - 1 year old Med. spur thigh

[achilles]

Hi Folks,

We have a lovely 1-year old Med. Spur Thigh who spends most of his days on a tortoise table, mixed terrain, under UV strip lamp and basking lamp. When weather has allowed it, he's been roaming (under close protection!) outside. His diet is almost exclusively weeds (once a week he has tortoise pellets) and we alternate sprinkling either Neutrobol or Calcium Carbonate on his leaves.

Today when bathing him I noticed there was just a hint of 'give' in his shell at the very back (the Supra Candal Scute?).

For about two or three days in the last week he was grazing weeds from the garden (therefore no Neutrobol or Calcium Carbonate) so we were wondering if this might be the problem? (lack of calcium due to no 'additives'?).

Any advice gratefully received. Thank you.