Any time you are growing in a container, you have a higher chance of running into nutrient lockouts, nutrient deficiency, and nutrient overloading. Depending on the severity (and this looks pretty minor), drenching the plant with water and letting it dry is usually recommended to help clean the root area out. This is usually only recommended if you have been adding more nutrients than what was already in the soil.
What I would recommend is capturing the run-off water from a normal watering (maybe more than normal just so you can a decent amount of run-off to test) and then checking the PH and PPM to narrow in on a possible issue. Sometimes the PH is out of whack and that results in some nutrients in the soil being unusable by some plants.
The trouble with diagnosing it based on pictures alone is that both nutrient deficiencies and excess nutrient symptoms are usually very similar.
Have you been adding any additional liquid fertilizer when watering? What was the soil originally (NPK)?