Losing your mucous plug does not necessary mean labor is near i t can still be weeks hun . I'm 40 weeks tomorrow and around 37 weeks I had lose bowels and nausea and really it could be anything there's more room for your bowels with baby engaging so it may have loosened your bowels up some or even something you ate . Let your doctor know though as well .
No one can really tell you when labor is going to happen, it just does. Nausea & loose stools could be something completely irrelevant to labor maybe a food adversion. If your contracting etc then I'd call. But loose stool could be possibly an upcoming labor I've read
Well if you start having real contractions they will be strong, and they won't go away just by changing positions or moving around. Although I can tell you, I'll be 37w tomorrow and I've been experiencing pretty much exactly the same, I don't think I'm anywhere near labor though.