Hello,
This is molluscum contagiosum, it is caused by a virus. This is usually common in children but can happen to anyone. Nothing to worry.
If it is increasing, in your case has been increasing then has to be removed by a dermatologist or else it may increase further.
This can spread to others too, hence must be careful.
Next Steps
Consult a dermatologist near by your house and let them extract this. It's a very small, simple procedure and helps get rid of this.
Health Tips
avoid the spread by keeping clothes, bedhseet separately.