My big toenail is white on one half and thick. what is it and what can i do for it?

Could be fungus in: the toenail. A doctor or podiatrist can evaluate and tell for sure. Sometimes the nail grows back thick because the nail bed has been damaged. A culture can be taken of the debris below the nail, or but cutting a piece of the nail and sending to a lab. fungus infections of the nail can be treated but the treatment is long and the nail grows slow so you may not see changes for months and months

Get checked.: Changes in nails can be due to trauma from bad shoes or improper trimming of nails or due to infection or other problems. See your doc or a podiatrist or a dermatologist and get the best advice, which can only occur after a good history and an exam. Consider a Prime Consult or a consultation with a specialist on HT concierge, if you do not have a doc.

Fungal: If no history of trauma to the nail, then most likely nail affected by a fungal infection. Needs to be examined to determine if that's the case, because treatment for a fungal nail infection is often months of antifungal medication