Doctor’s note doesn’t cover entire period where I was sick for special consideration

I got covid last monday to now (still not recovered) and I went to see a doctor today who gave me a doctors note and medication for today to the 26th. The exams office told me to get a doctors note that states the entire period for which I was affected which I told the doctor, but he told me that it was against the law to state that period from before I saw him. Can I still apply for special consideration for my exams last week if the exams office oversaw my illness?