Are you using ordinary tap water? These plants are particularly sensitive to this, or to be more exact, the Chlorine and/or Fluoride that is found in tap water. It would be best to use rainwater, distilled water, or even reverse osmosis-filtered water. Most people don't have reverse osmosis filters, tho distilled water is fairly cheap and can be found at any grocery store. But my recommendation is collecting and storing up rainwater. Plus, it's basically free to do so. And once you get the hang of it, it's really not that much work.

Well, I hope this helps. Maybe others might have better suggestions, but to me, using tap water seems to be the problem.

I forgot to mention, if the problem keeps progressing, then perhaps repotting it into fresh soil will fix it. This would help eliminate any traces of whatever was in the old soil that was causing problems for your plant. Continue to use the rainwater afterwards, to prevent this from happening again in the future. Good luck!

Great Thank you!

Would fountain water be okay during the dry seasons?

Thanks again!

While the plant is sensitive to compounds that contain fluorine, it's probably not a good idea to assume that reducing or eliminating the amount of fluorine your plant is exposed to is going to solve your issue. There are 2 reasons not to make the assumption. One is, there's a very good probability that fluorine (or chloramine) isn't the issue. Fluorine toxicities usually cause a lot of chlorosis (yellow foliage). Second, if it IS the issue, the fact that fluorine toxicity is caused by the accumulative effect of compounds containing the element means it's already in plant tissues at toxic levels.

Other possibilities include over-watering and/or a high level of dissolved solids (salts) in the soil solution. This plant is very sensitive to over-watering and over-fertilizing, or to not watering correctly, which leads to a high level of dissolved solids in the soil solution because you're not flushing them from the soil when you water.

Al

I would concider pulling it out of the pot to see what is going
on in the root zone, this might give you a better clue to the problem. If using public water, they always add things, I would switch to bottled water. Good luck.