What is causing my fingernails to split and break unevenly?

Fingernails have got weak and brittle ? This often is caused by a fungal condition and also you need to take some vitamins for this and get some fungal medications for the nails also and treatment for brittle nails include supplementation with vitamin A, vitamin C, vitamin B6, niacin, calcium, and iron.that can be gotten at the drug store and a better diet and not using fingernail polish and a host of conditions can help this but you must get this under control and find out for sure of what this is. and also lung or breathing problems can have effects on the nails along with low blood flow to the fingers so go to a good doctor and get this checked out.