How do I tell my sixth form?

I'm going into year 12 this year but i will most likely be resitting 3 gcse subjects and its NOT because ive failed - im predicting 887 in them - it's because i was sick during some of those papers and i know for a fact that if i was not ill then i would have got 999
so in turn if i was not ill during 3 papers then i would have got 7 9s.
I will be going to a grammar school sixth form which is better than the grammar school i currently go to so resits would be looked down on - therefore i dont want anyone apart from my close friends to know about my resits an i dont want teachers to look down on me - one of my resits are happening in November but the other two are in the next summer period when year 12 mocks will be happening. How should i tell my sixth form so they are informed about this and understand that im not resitting bc im dumb. im resitting bc i was ill?

Did you actually take the papers and get 887, or did you have to miss them? If you took them, I would simply explain what happened to the head and they wouldn't think you were dumb - they are good grades and the fact that you are so perfectionist in wanting 999 is probably going to be seen as a good thing. If you didn't take them, well - you've already obviously got 9s in other subjects so why would they think you were dumb? I wouldn't worry about it. Just explain you were ill. Wasn't your fault.

yes, i sat the papers and i reckon i got 887. Thank you, i will just simply tell the head when i start in September. Im probably over thinking - I thought it would make me seem quite dumb because most of the times only those who fail resit.