Hi, bjames. I don't know this specific plant
, but if this is it; http://davesgarden.com/pf/go/58543/index.html
then I can make a few suggestions. It looks like Euphorb milli/milii, finding out about that may be easier. That one's original plant
material is from Madagascar and Mauritius island, both very arid places with very poor soil. It evolved with no fertilizer and not much water. Grown in these conditions, "hard", it's not all that pretty. Most hybrids (denoted by the x in the name) and cultivars ("Sonoma") want better conditions to thrive. However, they can't go too far from their roots (ugh, that was awful. Sorry). So, lots of sun and a quick draining not very rich soil is in order, with some diluted fertilizer. No (that I know of) cactus
wants full strength fertilizer. 1/8 to 1/2 strength is good, the lower every time you water, the higher maybe in the growing
season. You say it has bloomed for you. When? For how long? How were you treating it at that time? Research will only get you so far, observing your plant
in its situation (humidity, available light, your soil/water/...) and remembering what works (take notes?) will give you more info. Just remember plants
don't react quickly. Good luck. Take pics. Tell us more. Happy New Year!