Treatment for visitors (like Dental,therapy,migrne etc.)

Hi ,
My mother is visiting me on visitor visa. As ususal her insurance covers for acidents and few illness.
She has a problem for which i need to see a physical therapist.
I was wodering can i buy insurance or does any insurance can cover such visits?
Does visitor insurance does not work like the insurance we have in states.noramlly they are good only for the accidental injuries or for problems no existing already before coming within six months.

If I want to have a treatment for my mother what is the best way? Can I take some insurance? or i need to pay all from my pocket?
Please advise.