New soil and a larger pot won't help much if it's a watering or nutrient problem.

Ph is the first suspect. Nutrient ratios and/or days, a close second. Or perhaps the acid rain...?

Filling-out the troubleshooting form will help. Until then it's guesswork.

Something you can do now: tilt the pot, and stick a finger in one of the drain holes to see how moist the soil is. If drenched, cut back on adding water.