Hello Jessie,
I can think of a couple of possibilities. The eye problem could be an irritation from the sand (especially if its at all dusty) or it could be from an incomplete shed. Does she have a humid hide? If not, you can make one easily from a quart size plastic butter/margerine container. Cut a rounded hole half an inch above the ground, large enough for her to easily climb inside. Use dried green moss (dampened) or a couple of paper towels (damp) in the bottom. Place it on the warm side of the cage.
For the feeding difficulty ... well, sand has been known to cause impaction especially in leopard geckos under 6 months. Sometimes they swallow some accidently and sometimes they eat it deliberately. Regardless, the sand can pile together and block the intestines altogether. You can try placing the leo in a small tupperware container with half an inch of water for 30-45 minutes. The water should be warmish, (baby bottle warm) and placed on the heated side of the cage. Sometimes this will work wonders.
In addition, I'd take a fecal sample to a vet. The sample must be fresh (moist). It can be refrigerated overnight if necessary, but not frozen. Leopard geckos can get pinworms and other nematodes. Most of these can be easily identified by a vetrinarian, even without specific reptile knowledge. Some protozoa etc. can show up too and that's where it helps to have a reptile vet. However, you can ask your regular vet to do a fecal float if you can't find another vet around.
Panacur is the treatment of choice for many nematodes, and 25mg/kg is the usual doseage rate. You can usually get leopard geckos to lick the medicine off their nose, and offer water afterwards.
In the meantime, be sure your temps in the tank are right - 88 to 90f on the warm side; 80 degrees on the cool side. A hide on the warm side and on the cool side. A humid hide (warm side, or half over the heat and half off). Relatively quiet area (no t.v. or loud music). Not held or played with until eating and drinking.
www.drgecko.com is a wonderful site with many useful resources and tons of easy-to-read information.
One more thing - fluids are even more critical to survival than food, and it takes water to digest. Pedialyte can be bought in small bottles from almost any pharmacy (under $2). I'd try touching a drop to her/his nose hoping the leo will lick it off. If the leo will take 5 drops or so, that's a very good sign. Repeat twice daily.
Sure do hope all works out well, let us know how it goes please.
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Andrea A. 
