I agree. The damage showing as yellowing and yellow spots combined with the curling of the outer edges of the leaves, tells me you have mites.
Yikes! Get out the Mite swatter!
Just kiddin.
Do some surfing on google for "Mites Marijuana" without the quotes. You'll have a wealth of information about mites and their cure.
The ones you have prolly have two black dots on their backs. Less likely, but still possible is another kind that is red. With a good magnifier, you should be able to see them clearly. They hatch every three days or so, so if indeed you do have mites, you'll have lots more very soon. You need to get hoppin.
You'll find pages that refer to:
Pyrethrum, Cinnamite, Neem oil and other resolutions are called "Miticides". Pick the one that's most suitable to you. You CANNOT put these plants into flower until you have this under control.
Good luck to you man!
Here's a good hint for you; After coming in from outside, especially if you've been in a garden or through a field of weeds, change your clothes and shower before going into your grow area. Mites don't magically appear. Someone has carried them in from another plant.