Here is a picture of it this morning, very quickly I have had leaves yellowing and dropping when a week ago it was perfectly fine.

Transplanting into a pot.

What is the rootstock of the tree?

How many days does it rain?

How often do you have this kind of weather?

I'd consider replanting it in a mound. Can you create a mound about a foot higher than the grade?

I'll second Dave's suggestion. I'm also in your general area, Beaumont, Texas area and I have learned to make a mound about a foot high (actually build it a little higher if you have the dirt handy so it can pack and slump some) and up to as bug around as you expect the tree to grow. I do have a nice Satsuma which I planted many years back just on level ground and it has done well so the mound concept is good but not always required, The other issue you may have as your tree reaches fruiting maturity is with fruit splitting from dry spells followed by our monsoons.

If you have space, time, and a place to get some river sand or other loamy soil, build you a big raised bed. Mine is 10'X10', about 12" high and is a great place to grow citrus and lots of other things around the perimeter.

I planted my montmorency Cherry tree in a mound.