when you say you water regularly, i take it you are growing in soil.... and that you answered your own question.....you "water regularly as well". that i think is where your problem is. you are overwatering. when in soil, you want to not water too often. try not watering until the soil is dry all the way through except maybe the bottom inch or two of the pot is still damp. then water again (not over watering). the reason for this is so the roots have to GO SEEK out water and go further downward and therefore the roots gets bigger and stronger.

after you said you water often, then in my opinion it was not hard to figure out. not only the spots, but if they start to droop, that is another sign of overwatering. hope this helps. take care