A good quality probiotic is beneficial when on an antibiotic. The key is to give it 2-3 hours away from the antibiotic (prevents the antib from killing it off). And then when antib. is finished to continue the probiotic for weeks or a month to keep putting good bacteria back into the system.

For instance when treating for Lyme with a month of antib. I continue with probiotic after antib. for at least a month.

No experience otherwise with what you are dealing with but prayers the treatment works for your boy.