Deformed plant (with pics)

Hi all
I`am 3 and a half weeks into my grow and my plant is looking weird.
The roots were slow to grow and now it seems to have stopped growing at the 3rd set of leaves.
Its tangerine dream growing under a 70w HPS in a bubble bucket.
Any advice would be appreciated.
Cheers

I am currently dealing with this on an ak-47 plant. Looking at your last picture your plant did the same thing. Something, whether it happened when it came up through your medium or whatever, the top got pruned or died therefore it is growing multiple stocks instead of just one center. All you did was top it naturally at the begining and you will have multiple tops with one or two being the main ones. I don't know much about the strain but alot of plants do better being topped. I will send you a picture of my plant and you can see what mine is doing. Hope I could be of some help

Actually taking a closer look I think you will have two large colas when it's all said and done