dendrobium kingianum with yellow spots

[1277cynthia]

I have a dendrobium kingianum (picture below) with yellow spots/patches on its 2nd newest cane. When I purchased it in February at an orchid show, it didn't have the spots, after it finished flowering, I repotted (pure bark). About 2 months after that, it started to put out a new cane and grew pretty well (especially since I bring it outside to get some sun), but about 2 weeks ago, I noticed the new cane stopped growing even though it's still tender and soft. Then those yellow spots started to appear. The roots of the plant still has nice green root tips, but I don't think they are growing as fast like before. I'm new to orchids just trying out new orchids that are not phalaenopsis. I read a bit on orchid viruses and pests but don't have any experience with it. could anyone help me identify what's wrong with my plant? I'm hoping this isn't a virus. Thanks

[wintergirl]

It looks almost like the plant was bumped in the area down the cane. Like it yellowed at the damage site. Just my guess.