Probably shock. 5 gals are not the most stable of plants. Best to keep them as is for 5 or 6 mths before replant. Shake out does harm to new roots. Lastly, keep new plants in the shade for a month or so. I'd try to keep it as is but move it to a shade area and cut back on water. If it's tall and spindly, I'd top it down 1/3 and cut off some low branches. Watch the main stalk not the leaves. It will regenerate leaves if the stalk stays healthy. Lastly, planting a aggressive running bamboo in a ceramic pot is not good. The roots will break it in a year. Go for a wine barrel, if it recovers.

thanks for the help. I will try moving it to some shade, and keep an eye on the water. what do you think should be a good amount to water? once a day? Like i said it drains really well i notice that the water runs out of the bottom as soon as i start pouring it in. but the Soil still stays moist most of the day. its in a 15 gal pot atm. much larger than it was in originally. And my plan is to upgrade the pot as needed as it grows until i reach the size i want and then prune it (rhizome splitting/pruning i guess) i have read that its ok to repot once a year into a larger and larger pot. Once its established in containers for a few years its ok to prune the rhizomes back. That was the plan, but is that not correct? Is it not safe to do that? Will I most likely lose my bamboo if I attempt that? Any other advice? I also have a very healthy P. Aureo "Spectabilis" that is doing great so far, one decent culm with lots of leaves and branches. How long should I wait until I repot. I bought it from a reputable nursery that has had it at least a couple months if not longer before i bought it (they dont do their own bamboo growing but have a reputable vendor that i believe is local) Its currently in a 1 gal nursery pot and I want to put it in a nice looking container for the patio also. Any suggestions as to when is best to repot?