Is there not a PDSA anywhere near you - if you are on limited income they may be able to help. Also speak with your vet and find out if there is an alternative cheaper treatment. Failing that see whether or not he/she will allow you to pay so much a month - lots of vets do if approached in a reasonable way. As for the balance thingie - the antibiotics need time to work - usually takes 24 hours to kick in then depending on how deep seated the infection another few days to see an improvement. Hope your dog is soon okay.