Brief Answer:
They can be prescribed for a wide range of infection...as explained below..

Detailed Answer:
Hello and Welcome to 'Ask A Doctor' service...
I've gone through your query in details...
I can understand your concern...

Firstly, please note that Trimethoprim and Sulfamethoxazole are also termed as Co-trimoxazole. It's a combination antibiotic which can be prescribed for a wide range of infections, namely- Ear infection, Bronchitis, Urinary Tract Infection or even as a prophylaxis treatment (preventive measure) of certain other bugs causing pneumonia.

Now, as per your description, it seems like the Rocephin IV and Doxycyclin course is already over. So, if you aren't aware of your doctor prescribing the Trimeth/Sulfamethoxazole, kindly check with your pharmacy.

Another possibility would be the doctor already mailed the latest prescription directly to the pharmacy, but in that case, also, this new antibiotic course should be discussed with you before initiation. Kindly reconfirm the same.

Let me know if I can assist you further.

Take Care
Kind Regards

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