Most likely bloat or a mild form of SBD- in the cups they aren't usually fed or they are too stressed to eat, so a system going from no food to being filled up can case trouble (in time she should be fine, go ahead and start out small, 1 pellet per meal twice a day for a few days, then 2 pellets per meal, etc.) Give her a day to digest it all with no food to catch up.
CVS may carry it- most pharmacies and places such as Walmart carry it for pretty cheap.
Start her out at 1 tsp per gallon, dissolved prior to adding her in it- use water conditioner, daily 100% water change. It can take 8-10 days for them to be fully recovered. If by the 5th day she still is having issues, up it to 2 tsp per gallon.
CVS company caries them- just make sure it's dye and fragrance free.. CVS Epsom Salt
Let us know how she is doing and if her symptoms change any.. good luck!