Answer: How upsetting!
Based on your description, it sounds like your geranium suffered some transplant shock when you dug it up. If you try to do this to a geranium, you need to trim back the top, probably by at least half, to compensate for the root damage and disturbance caused by digging it up. When you pot it, you need to use a well-drained potting soil mix because the roots will rot away if they are kept too soggy.
Bringing the plant indoors causes yet another shock, so your plant has had a double whammy. It's best to acclimate the plant slowly to being in the lower light available indoors; to do this gradually move the pot into shadier and shadier positions and finally bring it indoors. Ideally this takes a few weeks.
Rather than digging the whole plant, some gardeners use a different method to hold over geraniums. Some grow the geranium in a pot and then bring that in for the winter. Others take cuttings instead of saving the entire plant. This saves room in the house and gives you vigorous new plants to winter over.
Indoors, geraniums do best with as much light as you can give them; they also like cooler temperatures at night if you can provide them. Water thoroughly and then allow the soil to dry out a bit before watering again. Finally, since they are growing more slowly in response to the less than ideal indoor environment, they need proportionately less fertilizer than they might outdoors. When you fertilize, be sure to follow the label instructions carefully.
Since your plant is doing so poorly, you might wish to try the following: cut it back by about two thirds and repot it in fresh potting soil mix. Water it well to settle it in, place it in the sunniest spot you have and then follow normal care as outlined above. Be patient and see if it resprouts.
The National Gardening Association (http://www.garden.org) operates a seed swap.
Good luck with your geranium -- that is a pretty one!
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