It really sounds like you need to get the tortoise to a vet. In the mean time make sure the tortoise has temperatures in the range of 80 to 100 degrees F. That is a cool end of 80 and a basking spot of 100 . Also make sure the tortosie gets a daily soaking in addition to a shallow water bowl in the enclosure.

Try to provide food in the form of dark leafy greens such as romaine, escerole, dandelion greens or the like on a constant basis.

Again, you should schedule a vet visit and alos ask the vet to do a fecal. If you have a Greek it is probably an imported wild caught animal in which case it is probably really stressed both physically and mentally.
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Ed @ Tortoise Keepers
Trying to keep the fun in Chelonian care