That's normal breathing. Their lungs are on top right underneath the shell. This prevents the tortoise from breathing normally like we do so they have to regulate breathing by pulling their legs in to release oxygen and pump them back out. They also smell with their throats. When they suck themselves into their shells they are holding their breath. They are more tolerant to Co2 than we are so this allows them to stay inside and protected for a long period of time. Hope this helps.
it appears that the set up you have is too dry and not very accommodating im not trying to be mean but there is a lot of good info here that can help.if you can do some research on the proper care you will see what i mean . @Tom is a wizard and leader of the pack on this,
