Hi!! Yes, sometimes they do that when they're missing certain nutrients from their food.
And oh boy
IAMS is not a food that I would recommend for any dog. First, they do animal testing. You can google this and see the horrible stuff about it. Second, it's full of by-products and fillers.
Take a look at
www.dogfoodanalysis.com and look at the 4 and 5 star foods. These are much better alternatives to Iams. Take a look at why Iams scores so low, so that you can get a better understanding of which ingredients to avoid.
Good luck!!