Toenail fungus is medically known as onchomycosis or tinea unuguim. I would recommend that you see a dermatologist
in order to have this addressed. In general, you have gone through the standard treatment. As such, seeing the nail specialist (the dermatologist is a skin and nail specialist) is recommended.
Onchomycosis is a fungal infection that gets deep into the nail. It requires oral treatment as simply topical treatment is not always able to penetrate. That being said, there is some data to suggest that combining pills and topical treatment can help the most resistant infections. Nail paints like amorolfine or ciclopirox can help.
The next step would be to try a different anti-fungal pill. Lamisil or Terbinafine is a great medication but rarely a fungus can be resistant to this. Other antifungal pills that could be tried are itraconazole or fluconazole.
The other reason to see the dermatologist is to make sure this is the correct diagnosis (that is to say we have to make sure this really is toenail fungus). It is so rare that Lamisil doesn't work, we should make sure it is not something else.
See a dermatologist. Good luck!