So,
the vet was just perfect. Nurse was holding him, he was still (never so still with me, lol) and the vet cut his nails... she was nice and everything went ok
!
Im so happy!
Also she said that he is um...fat. He needs to go on a diet - she said that he is probably just lazy and thats why he is fat and his nails grew that much. She said that only thing i can do (except what i already have - wheel is ok and he doesnt get sunflower seeds etc.) is to give him less food... so poor Sheldon has to go on a diet.