Help Regarding 4-month Old Refusing to Drink Milk

I am hoping someone can offer some ideas or suggestions … we live in greece and have a baby daughter who will turn four months old on june 26th. She developed a urinary tract infection at just over three months and after an in-hospital course of antibiotics, she is clear. She continues to take oral antibiotics, at first septrin and now ceclor. It seems that after starting the oral antibiotics, she has slowed down seriously in her milk consumption. Before she would eagerly drink about 150 ml (5 ounces) in two or three goes five to six times a day. But now she takes only about 2 to 3 ounces on the first go and absolutely refuses to take any more. We are trying to feed her every three hours but she refuses so much. It is almost like she dislikes the milk. Her urine re-test is still clear. She seems to have a lot of indigestion and gas and the doctors here have given her zantac to stop this but after four days it is not showing much effect. She is in the process of adoption so we can not take her out of greece until her paperwork is complete. We are very reluctant to travel to athens as we fear she may catch something else worse … athens is horribly hot and dusty in the summer. I would very much appreciate any ideas or experiences. Thank you!!