Friend in need, Desert Tortoise sick

Her Desert Tortoise has not started eating much and is not coming out of hibernation mode seemingly, so she took him to the vet and he said he needs more sun so she puts him outside and still not eating, now he is foaming at the mouth. All the things the vet said, was he ate something sour, NO, he did this or that which was all no too, any ideas? The vet gave him a shot too. $180 later, she is worried.