Splinter can be easily remove with sharp and sterile needle. Just soak the needle into 70% alcohol and use it carefully.

splinter in our soul need much more than that, you may need to seek advice from other. I myself would see for advice when I face it, and sometime just lets it goes.

for the callus under skin if it contain pus, you may need to take it out and put antibiotic afterward. But if you get callus in your heart that is really difficult to rid it off. One suggestion for anyone: Lets it goes if you can even if you can return it back. And proceed it to police if you think necessary to give a shock therapy and good lessons to others.

The best way is see medical treatment.

Wish you happy family @sumatranate