Hi there!
I am not sure what is going on...I am not qualified to give you any speacial recommendations at this point . Have you seen your physician lately and told him about your problem? The best thing for you would be do that and make it a priority.
sometimes infections may cause weight loss but it is very rare. contact your physician and ask him the reason for your weight loss. follow his auggestions
Being ill can cause weight loss and the fact that you are on anitbiotics - you may actually be eating less than you think you are.
I third the opinion that you should see your doctor. I would specifically recommend that you ask to have your thyroid checked as it's possible that you might be "hyperthyroid" which means that your thyroid could be working overtime, which speed up your metabolism, since thyroid pretty much controls metabolism.
Just a thought and it's very possible that there's nothing wrong except that you don't feel well with the ear infection, etc, but still worth getting checked out.........