I'm late to reply here but I would like to add a few comments.
Whatever you sprayed on the plant should be washed off, in a definitive way. Take a few minutes with a spray bottle next time you water the plant and go it at from all angles with plain water. And do your best to make sure it dries out soon afterward.
This will give you a baseline to judge if the accumulation you've seen is chemical or fungal in nature, and whether it spreads. You will have to revisit the plant (check it each time when you water) to know that.
The usual prescriptions for fungal issues often relate more to prevention than treatment. You want to make sure light is not limiting, and also see what you can do to improve air flow. Strong light, warmth, and good air flow are all helpful there.
As for encouraging strong growth and a more compact form, it would be best if you could provide the maximum possible amount of light if this is an indoor plant. Find a spot right in front of your sunniest southerly facing window. The plant should "see" the sun for hours a day, year round, with no curtains or blinds in the way. With good light and regular water (waiting for the soil to go nearly dry each time) the plant should outgrow whatever crankiness it seems to be displaying right now. Do not move it outside into full sun if it's been in a protected indoor location or you may shock it into oblivion; give it a week or two in bright shade (no direct outdoor sun) or filtered light instead.
Here by way of illustration is a picture I took exactly 12 years ago today.
This is what you get when you turn the light up all the way (here in full sun, outdoors).
