Denny, where are you located (ie what growing zone?) To me your soil looks awful wet, but that could be from a recent rain? In any case, browning of the tips like that often indicates too much or too little water. As wet as your soil looks like, probably too much. I believe Mangos prefer less water during the cold winter months and then lots of water during the summer (opposite of what I get in San Diego). Someone more knowledgeable can probably help more.

I live in South Florida,

I was thinking that maybe the soil is too wet but i purchased Citrus Potting Mix which is suppose to be fast draining? This started happening about 3 months ago and before that the tree was doing just fine in this same soil.

Also as you can see in the picture the older leaves don't seem to be affected as badly as the new leaves, I don't know if that can be an indicator of the problem.

It could be anthracnose which can be common in wet weather. Or a build up of salts in the soil. I'm hitting the limits of my knowledge....another good place to try is the Tropical Fruits Forum