You first visit a dentist and find out whether, dental implant treatment is possible in that missing tooth area or not.Cost depend upon various different systems of dental implants. That may include dental implant and crown.About the age is not a problem here. You should be medically fit without any major systemic disease and that missing area should have good quality bone to hold the implant.
Next Steps
Visit a nearby implantologist and get the replacement of missing tooth done. Above toothache, it will be taken care by your doctor with the help of proper medicine during and after the treatment.
Health Tips
Don't delay for replacing any missing tooth/teeth. There are other treatment options for replacement are also available like dental bridge or denture.