Sand stuck on my clowns or ich?

Really need your advice. Ok so i have a 50 gallon hex tank cycled it for almost 4 months with live sand. Added two young clown fish false percula two weeks ago and they were doing great!! Was so satisfied with the outcome as I was so patient and it seem to have paid off! Before we left for work yesterday all was good fed them everything was fine but when me and my fiance were at work one of the power heads tilted at the sand bed and blew sand all over the tank.. when we got home 8 hours later my two clowns seem to have sand stuck all over them, they look dull and very. Unhappy no shine and lost their vibrant color is seems i feel very bad for them! I have done a lot of research on ich and i hope these are just sand particles but today when we woke up they looked the same.. will this sand fall off? Im scared the sand storm stressed them out and i am a beginner so my mind is racing i dont wanna over think it and cause them anymore stress but just so sad that this happened because everything was going great !! Any info or advice would appreciate it!