It sounds as if you’re having a tough time with your symptoms. You’re not being paranoid and it’s understandable to be concerned about your cough.
It’s not possible to say what your cough and shortness of breath is due to. It may be a viral illness or could be the COVID19 virus.
It’s important you contact your GP to discuss this. I’m unsure if you’re still in contact with your treatment team. If so, it would also be a good idea to get in touch with them to ask for their advice.