If I have understood you correctly, you are asking about finding a flat share for August.
If you are looking for temporary accommodation, you might try some of the Swiss small ad websites like anibis
, petites annonces
. You will, of course, need to be able to spell 'Lausanne' correctly to find appropriate adverts on any of these websites, or to post an advert yourself.
I will give you the advice my mother gives the many, many people who contact our church asking about temporary accommodation in Lausanne. Accommodation in Lausanne is at a premium. Most people live in flats and do not have spare rooms. So unless you happen to find someone who is going on holiday for the exact time you will be here and is willing to rent out their flat / room... you may well find that the student buildings are your best chance.