Its time for a veterinary visit. Sneezing doesn't usually just pass, it usually is a sign of an upper respiratory infection and will require medication from a veterinarian to treat. URIs in hedgehogs, if left untreated, can quickly progress to pneumonia. You may have no symptoms one day and a couple of days later be dealing with something much worse. Hedgehogs are amazing at hiding illness, they will act otherwise normal for as long as they can despite being extremely sick.
Probiotics are good for fixing bad flora in the GI, giving it a boost when they are on antibiotics, or have green stools from dietary changes or stress. They won't fix a URI.