Drink lots of water, and keep checking your ketones.
Have you been drinking enough? Concentration of urine plays havoc with the ketone readings.
And have you been eating? Starvation ketosis kicks in otherwise.
Personally, I think those Ketostix are pretty useless, but the alternatives (buying a meter and strips that test blood ketones, or one of the other gadgets are very expensive)
And hypochondria - or feeling like a hypochondriac - is traditional. I have had the Black Death and Meningitis, don't ya know.
Just bear in mind that as an RHer, the odds of ketoacidosis are minute.
So unless you get up higher (I will hunt out the graph, but I think it is over 13) you aren't being harmed.