I had an outbreak of redbugs last year and my search took me here: Red bugs are tiny, pinhead sized parasitic copepods. They are more orange in colour than red and crawl all over. If your SPS has suddenly turned pale or the polyps are not openning, take a closer look at your SPS.
A word of caution: You may want to try a Yellow Corris first since an overdoze of the medication can wipe out all your all copepods, your snails, your detrivores and your shrimps.