Coton cough

When my 5 month old Coton gets to running in circles, or is jumping a lot, she starts to cough. It doesn't last long but freaks me out when it happens. Does anyone else see this? She's had all her vaccinations at the times they are due. She has had a problem with worms, probably due to her scavenging behavior when she's out on the leash to potty. We've been trying to prevent her from this, but a sniff does still sometimes turn into her munching on something as I desperately try to get stuff out of her mouth. Any ideas about the strange cough is appreciated.