Help my puppy chewed a bone and ate most of it!?

I got him a bone from the pet shop, and he was chewing it so much I realised he had been swallowing bits. The next morning he didnt eat much food because he was constipated, he tried going for a poop so many times his bottom was all red and soar, even bleeding a little tiny bit. He went finally and it was really hard. He has been drinking lots of water and eating his biscuits as much as he can too... but he was sick once, and now his nose is very wet and snotty. He seems okay, still playing and stuff. Is he going to be okay? Has the bone just made him constipated and his body is trying to pass it through, or has it actually damaged his insides?? Is there any food or drink I can give him to help him pass it through? PLEASE HELP! Thanks so much... xx