Please help me check this

Dear teachers,

Could you possibly check that my writing below is ok?:

Situation: Mr.A started to be sick/ill 3 days ago.Now he is still sick/ill.Now he writes this letter to explain why he has not finished repairing the television for his friend until now:

Dear B,

I have been sick/ill for several days (now )/for a while (now),so until now, I (still )have not finished repairing your television.Please wait for a few more days .I will sure start to repair it for you as soon as I recover from my illness. Now I am still in hospital for continued treatment.I will let you know when I finish repairing your TV so that you can come to take it.

Best wishes

Suppose "I have been sick/ill for several days (now )/for a while (now),so until now" is ok,is there any difference between " "I have been sick/ill for several days (now )" and " "I have been sick/ill for a while (now)" ?

Thank you in advance