help!!!!

[crazyivor]

i recently rescued a caterpillar from a very busy road near me and took it home, it was barely moving but if i gently touched its tail it would move forward a little, to make sure it was ok i put it in a tub with small holes in the top put some damp soil in the bottom and a few sticks with a variety of fresh leafs but after a few days it seemed to change colour and go hard so to me its either dead or in a cocoon what do you think?