Thanks for your query.
I will try my best to provide you with best possible professional recommendations to your questions.
is responsible for your blocked ear. I advice you not to take the metronidazole
I advice you to do salt water gargling and steam inhalation.
As you have mentioned you have cold for nearly 7 weeks, cause for that should be found out, usually it might be allergic.
If you have fever
you can take over the counter drug like paracetamol
It will be good if you get your Comlete blood picture, a routine test done and you can meet GP with that report.
Yet again, I do hope that you have found something helpful and I will be glad to answer any further query.