Brown spots on leaves ?

It's hard to determine the exact problem from those pictures and the limited info in your diary but from the looks of it seems like your plant is suffering from either a Phosphorous (P) toxicity or Nitrogen (N) toxicity (it might be both!), and some water damage! First fill your pot with a bit more soil, covering the stem and leaving about 2.5cm/1inch of it above ground. Check your pH to make sure it is in the correct range (5.5-6.5) And when irrigating try watering about 1/4-1/3 of the pot size (i.e. if you have a 11 liter pot then irrigate with about 2.5-3 liters) and make sure there's more than 20-30% runoff!! making sure there's runoff coming out of your pot ensures even spread of your nutrients and will prevent salt buildups in the soil. The frequency of the irrigation should be according to the topsoil of your pot! let the top 5cm of your pot dry well before irrigating again, don't let it dry completely though! (the root system needs Oxygen to grow as well and by irrigating too often without letting the soil dry the roots would suffocate and die) The best method to check the soil is using your finger! shove your finger into the soil, about first-2nd knuckle deep and if the soil is still damp then wait another day, if the soil is dry then it's time to irrigate! Hope this helps! Good luck and happy growing :)