When you post up asking for questions on issues like this, help us out by providing as much information about it as possible.

For starters... I need to know what soil you are using and the pH of your water source. It appears as if you have some kind of soil that isn't a very good choice to grow MJ in (looks way too woody). Anyways, when I look at "the Bible", the only deficiencies that you may be running into is an early P or Mn deficiency, but I'm not sure on that one bit. You could also have nute lock out. If that is the case, you will start to see more than just some spots on your leaves, so you'll know if that is it.

I'm willing to bet that getting some quality soil and a pH meter would be your best bet. Best of luck.