After i walk for 1 or 2 miles, i strat getting dizzy with balance problem and sensation like i wanted to fall. what could this be.?

Sounds like: Vertigo. I am not sure why it is induced by walking. Vertigo is usually relieved by keeping your head still while lying down and looking straight up at ceiling. If it persists, see your doctor because certain tumors can cause it too.

Certainly check with your physician, as you may have anemia, hypoxia, thyroid problems, low blood sugar, circulatory issues, etc. Since multiple possibilities, it is not feasible to be precise, so, likely will need to have several studies to pin down.