Hello, my name is***** board certified MD.
I am sorry that you are having symptoms.
You are correct in your suspicions. There is, in fact, a rare yet serious potential interaction that can occur between citalopram and clarithromycin. Symptoms include irregular heart rates, palpitations, shortness of breath etc.
As I mentioned, this is rare. But in people who may have predisposing conditions (such as electrolyte abnormalities caused by illness and inadequate intake), it is certainly possible.
Your best option is to ask your doctor for a different antibiotic. For your symptoms that seem to be consistent with bronchitis, doxycycline would be an acceptable choice.
And at some point, you may also want to completely stop taking the citalopram if you feel like you no longer need to take it. Since you are on the lowest dose of the medication, you can just take it every other day for a couple of weeks and then stop it.
But of course, make sure to discuss any medication changes with your doctor so he/ she is aware.