Answer: Well, based on your description I'm not sure what is happening but it doesn't sound normal. Generally these plants bloom well indoors if kept evenly moist yet not soggy, sit in a bright location, and are fertilized regularly with a houseplant type fertilizer according to the label instructions. When they stop blooming it can be because they are in need of nutrients and so fertilizer would be one thing to try, it could also be because the soil is depleted or the pot has been outgrown, it could also be because the plant needs more light than it is receiving.
If you used spikes intended for houseplants according to the label instructions I doubt they caused the wilting. Wilting (and leaf drop) can be caused by overwatering (surprising but true) or underwatering, by root damage, or by an insect or disease problem. It can also be caused by cool temperatures. You might want to take a very close look at the plant for signs of any of these other problems.
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