Hello my good man! According to the marijuana deficiency chart, I would say your symptoms look closest to a Potassium deficiency! When your relative humidity is low, you can almost bet your going to soon get a potassium deficiency from your plants perspiration. Potassium can get poorly absorbed when having too much Calcium or Ammonium nitrogen, and maybe cold weather. Potassium gets locked out of soil growing at ph levels of 4.0-5.5!
Potassium is absorbed best in soil at a ph level of 6.0-9.5. (Wouldn’t recommend having a ph of over 7.0 in soil) anything out of the ranges listed will contribute to a Potassium deficiency.