Since it's almost impossible to over water bamboo, and the tips of the leaves are brown and dry, I would suggest increasing the water. The soil in that spot may be slightly different or it gets more sum etc. I had a similar problem with the Buddha's Belly in my garden. The extra water solved the problem but created another... it grew into a monster that ate that part of the yard.

Looks like salt burn to me. I'd heavy water to try and force the salts down and then go back to your regular watering schedule only follow the above advice and increase watering duration.