Hi @HZMom I posted about my chin 2 years ago. All MRI's were clear, dental X-rays were clear, neurology examination was clear, everything was clear and I'm still here 2 years later with a numb chin.
Numb chin is only marginally related to cancers. I found a lump near my arm pit last year and while in hospital getting it checked at the breast clinic I mentioned my numb chin, the Dr had never heard of a numb chin being assiciated with breast cancer, and this was her area of speciality. So Google saying its mostly linked to breast cancer, what it should say is that its very rarely linked to cancer, but on the rare case it happened to be breast.
There was a health forum on Google somewhere full of people who all panicked after searching Google and who all revisited the site regularly for years reassuring they were fine, most never got to the bottom of it, some got better and some still had a numb chin. It could be as simple as nerve damage.
It's always best to get it checked tho of course. I recommend making a dentist appointment as well as they will want to do a jaw x-ray and examination to rule out dental issues.
If it helps to reassure you, the neurologist told me that all the really bad things it could be would be happening alongside other serious symptoms and you'd notice a quick decline in health. If it's just a numb chin and not really anything else then it's most likely not serious. I hope you get to the bottom of it 