Check for pests, take a look at the buds to make sure you haven't caught any bud rot.

Unfortunately it looks like you have mites. Use a jewelers loupe or something that you can zoom in with and look under the leaves for mites. It's honestly too late to do anything about it at the stage your plants are at, so you have two options. You can either harvest your plant and smoke the bugs (yuck), or toss it out and start over. Either way you need to clean your grow area really well before you start your next grow. Next grow cover the top 2" of your soil with diatomaceous earth. There's sprays you can use to keep them away. You can also order predatory mites online that eat the bad mites. Lady bugs can help too. A supplemental UV-B light can increase THC production by as much as 40%, but they also help guard against pests and powdery mildew. If you keep having issues with pests you might want to switch to hydro or coco. You're much less likely to get pests using those methods. Good luck with your future grows. Sorry for the bad luck.

Hey buddy, I don't think you need to worry. It's really at the end and soon you'll be ready for the harvest :) congratulations on the grow, it's looking great. Hugs and good luck with the rest!