That soil looks pretty dry to me, looks like a nut. def. to me.
I'm with toolong here; She's wilted, and possibly heat stresses.
A half gallon is not enough to thoroughly saturate the soil in that 5 gal pot.
Give her the 1/2 gal 0 wait 10 minutes (for the soil to wet) then give her another gallon. It's fine if 20% runs out the bottom.
Add a couple drops of dish soap, and it will help the watter penetrate the soil.
Only water again once it starts to dry out - when the planter feels light.
Re-potting wont hurt either - you'll be able to go a couple days between watering's in the new container IMO