Please Hartley, bring to the discussion an explanation that contradicts this, but explains a young woman retiring to bed after leaving a disgraceful and negligent hygiene construct.
Obviously we are all speculating, however:
There are various items of clothing soaking in preparation to be washed, items belonging to both Sheila and her children.
Is it not simply the case that either Sheila, or more likely June, gathered up the dirty washing earlier in the day, noted some items required soaking and so placed them in a bucket of water?
As for the tampon box or applicator, I have not in my experience, known people to have left such things lying around in living rooms, it seems a strange place for it to be. Hence my suggestion that it was placed there by JB to further enhance the perception of Sheila moving around the house and acting weird.