I would be very careful of your vaccinations until this gets resolved. In fact, I wouldn't vaccinate until you know what it is and are treating and it's resolving, which means keeping your pup very safe and protected and not exposed.
Clindamycin should be given with probiotics (separated by at least 2 hours apart) - that's a big time antibiotic. Following with the probiotic after the abx are done is also very important. They make probiotic powder for kids, and you can mix that in with some yogurt or organic applesauce as a nighttime treat.