Hi all, I have a purple shamrock growing in my apartment which I bought it around St. Patrick's day from the grocery store, and I think some pests may have hitched a ride on it. I've been noticing that every few days, one of the shamrocks dies. It shrivels up, and I'm able to just lightly pull it out of the soil. I thought it was natural, that they were old and just died, but today when I pulled one out, I noticed a tiny (1/4") worm-like (or maybe millipede-like) grayish (possibly transparent) insect wriggling around on the plant stem. So it seems like whatever it is eats the stem at the base and is killing my plant!

Does anyone know what this could be, and how to kill it? I've been spraying it with insecticidal soap once or twice a week (I also had a fungus gnat infestation on some cat grass i got as a gift, which ended up spreading to my other plants) but it doesn't seem to be working.

Any help would be really, really, really appreciated!