Yes, it is best to check with your vet in case they need a sulf antibiotic. You can get some online without a prescription, but they probably would not arrive in time. They may not need sulfa at all, but I just wanted to mention the possibility. Corid usually does a good job, but coccidiosis can cause damage to the intestines. Sulfadimethoxine is one sulfa drug that is sometimes used, and usually is prescription only, but can be found here for pigeons:
https://www.jedds.com/shop/medicox-100-g-medpet/
https://www.jedds.com/shop/medicox-100-g-medpet/