Mangoes can take lots of water especially if it's hot and sunny. Here in Florida it pours every day and they're perfectly happy as long as the pot has drainage. But you won't be able to grow it in a pot for very long, once it starts up growing again.
The tempoeratures you've been having, 100's right? aren't normal for mangoes and they should need to be watered every day when it's that hot. Here in Florida where every house has a mango tree, we get mid-90's at most in summer, and tons of rain. Otherwise, 80's are more normal, but high humidity.
My first advice for you would be to turn the pot on it's side and slide the root ball out to have a look. The soil doesn't look to me like it is too wet. It could be that it has compacted and baked itself into a 'brick' so the roots of your plant aren't getting any of the water you're giving it, it's just flowing right through. If that's what you find, crush up the root ball, and wash away some of the old soil. Re-pot with fresh potting mix, soak the whole root ball in a bucket of water for a couple of hours to re-hydrate it. Then keep the plant in the shade for a couple of days, and gradually re-acclimate it to the sun, moving it very slowly.
Fruit trees need full sun and consistent water. Let us know what you find in the pot.
