That small white patch may become a problem. Keep an eye on it.. It could of happened from a number of things, most common is heater burn.. Use Aquarium Salt and high temps, lots of good nutrition and water quality.. Rays are very good at healing themselves, but the conditions have to be right.. Stay away from Pimafix and stuff until you absolutely have to.. Never use Malachite green.. Its very juvenile and probably stressed, so no meds if you can help it.. Lights out and lots of food.. no stresses, keep an eye on tankmates, if any.
You can definitely tell it needs some weight.. if you can see the veins in the disc, it's emaciated..
They won't choke, they are smart..
Feed it until it won't eat anymore.. "J-lo Booty style".. Do this 3x-4x a day until you start seeing it put on weight and it's disc will fill in with color and no veins.. They can't overeat, but you can overfeed the tank and cause ammonia spikes, so keep an eye on that..