What kind of deficiency could this be ?

Just read your grow diary... You started to flush her...which means she doesn't have food... She's flushing...she's gonna show signs of nutrient deficiencies...

If the issues started with the lower leaves and worked their way up its Potassium. If it started with newer leaves first, its Manganese. What are you feeding, and how often? If you're feeding and she's still showing deficiencies, then her soil pH may be off. She can only absorb certain nutrients in certain pH soil. If you have/can afford to get a pH pen designed for soil then that would be ideal. If not, you could take two soil samples and place them in two separate glasses, add distilled vinegar to one and listen. If it sizzles, then the soil pH is too high. If you don't hear anything, take the other sample and add just a splash of distilled water to dampen the soil. Then sprinkle in some baking soda, and again...listen. If it sizzles then your soil is acidic. You want it slightly acidic, somewhere between 6.0-6.8 If your soil pH is too high or too low, then you need to do a flush with distilled water and wash out any nutrient salts that may have built up. Now obviously, if you havent been feeding her than all this is mute...