Citalopram is one of the SSRI antidepressants, and these often cause some relatively mild nausea in the first week or so. As your doc says, on ANY drug, it takes a wek or two for your body to properly adjust to the presence of the new chemical. And a muzzy head is also a common early side-effect. I don[t see how a chest pain would be related to the medication. I don't recognize the meds you say you are taking for the infection, but this on its own might be causing your symptoms, and also such drugs can intefere with the metabolism of other drugs, and cause some side-effects in combination which they may not produce alone. But I'd assume that your doc has checked out the possibilities of unhelpful interactions between these drugs.
Dizziness and sleepyness are quite common side-effects of antibiotics.