Sgdlboy, fellow support group -
I tend to be another believer of; something needs to be said at home. For all you know, your mother might be really upset, concerned or stressed about this. It could be eating away at her more than it is for you. I take it that this is your biological mother, the great lady who brought you into the world? There is likely nothing or nobody she cares more about in this world, than you (and perhaps your siblings I believe you mentioned). I think you might owe her a slight explanation at least... just in case..
I do however believe there might be some middle ground...I would also not recommend making up medical issues, as that is likely to cause more worries, concerns and possibly even guilt feelings for her. On the flip side, I am not sure that you need to explain that it is a kink, that gets you excited and what not.. how about the approach of, it was something you read about, and how it can be relaxing etc. You tried it a couple of times, and it really helped calm you and settle you down. Heck I am sure she would rather you do this (rather innocent thing) versus resorting to drugs or excessive alcohol as many do. Apologize that you left it out, and be clear that you never intend to wear or use around her and you would prefer if she could just not spend too much time or energy thinking about it. It is harmless. It is a little strange yes, but it is something "practiced" by people around the world, and again is a truly innocent act. You are still the same person, bla bla bla. Leave it at that and I am pretty sure she will move on...
I wish you and your mother all the very best.
-andrew