Hi,
The black spot could be a pit cavity or some stain
And there is no home remedy to treat it
You will need need dental help for sure
Please do not fall for any youtube / facebook home remedy with soda, peroxide or anything of that sort at it may do further damage to your enamel
Next Steps
do not get worried, go to a dentist and get it addressed
it may be just a stain....
hope this was helpful to you!
Dr. Prachi Lalji