Gailo, is it a running bamboo or a clumping type?
If it's a running type, i suggest you dig it up. It will own your yard and the neighbours yard too. Almost impossible to get rid of.
If it's a clumping type, it may be suffering from transplant shock. It's the middle of summer afterall. I suggest you cut it back a bit and check to see the water you're giving it is getting to the root zone. They like plenty of water while they are actively growing but they don't like it to be boggy so drainage is important.
If the moisture levels seem OK in the soil, try giving it a weekly drink of seaweed extract. Don't fertilize until you see it pick up.

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The secret is the soil.