Please help

Hello everyone, I am new to this so please help. I am growing a few plants for medical reasons. My favorite plant has started to have brown patches on the leaves and become brittle. I have read many pages on deficiencies and PH, but because I am new to this, it sounds very foreign. I have transplanted my plant from its original growing medium of a cup with soil into a larger pot until the weather is stable enough to plant outside. I have given it nutrients and plenty of water to keep the root system moist. It continues to have patches appear. What do you think is the problem?