Spots on the leaves

First of all, without a diary, we don't have any information except what you've told us: 1- there are black spots on the leaves, 2- it's been flowering for 6 weeks. That's it. The picture quality is also not very good unless the leaves are truly this dark... but I CAN tell you it's not calcium deficiency because the spots would be accompanied by a yellowing of the leaves. I agree with @Roberts that you've got signs of a nitrogen toxicity (leaves curling, terribly dark leaves) ... but we have no information as to WHY... it could be you're overfeeding nitrogen, it could be your PH is not in a good range, it could be you haven't been getting any runoff and therefore the nutes and salts are building up in the soil.... The spots are difficult to say anything about particularly because the photo isn't very good... they could be a whole range of things from a micronutrient deficiency to fungus... I'd even say it could be septoria which would be a MAJOR concern for your grow. Do yourself a favor... start a diary and try to get better pictures - the more information we have, the better we will be able to help you! Good luck.

I'd also say it's calcium deficiency, check your water for calcium, check your soil for low pH. Get well soon, plant!!

The curled leaves is nitrogen toxicity. The spots and discoloration is calcium and potassium deficiency. Usually when I see both it is a ph issue in soil or substrate. Which is from a lack of run off from adding nutrients. So the salts have built up in soil causing havoc to plant. I recommend a flush of substrate and testing run off for ph and ec. If you had not been getting 20 to 30 percent run off on feeds then that will be the issue for sure. Best I can figure with available information. Good luck 👍