Hi Saam,
Here are some options on cities and websites where you can **** for housing. I hope it´s helps you to get started!
FREIBURG:
Freiburg University Medical Center (****://***.uni-freiburg.de/universitaet-en/uniklinik)
The city isn´t huge but it is in the south of Germany!
Apartments in Freiburg:
https://***.facebook.***/Wohnungen.frei.in.Freiburg/
****://anzeigen.badische-zeitung.de/miete/wohnungen?16_ro=1
Resources where you could get in touch with groups in Freiburg, and search for an apartment in that way:
****://wiki.freundeskreisasyl-freiburg.de/doku.php/organisationen:initiativen
LEIPZIG:
Medical School:
https://leipzigmedicalschool.de/
Apartments:
****://***.kontaktstelle-wohnen.de/index.en.html
****://***.wogetra.de/
****://***.lvz.de/Anzeigen/LVZ-Immo
The first website looks especially good! There is support provided in the whole process.
FRANKFURT AM MAIN:
Medical School: https://***.carl-remigius.de/standorte/frankfurt-am-main/
Apartments:
****://***.immo-rheinmain.de/
Pro ASYL is based in Frankfurt am Main and may be able to provide assistance:
****://***.vielfalt-bewegt-frankfurt.de/de/netzwerk/pro-asyl
Caritas also for assistance. Contact info is at the bottom of the page:
****://***.caritas-frankfurt.de/51019.html
Also if you find a city that you are confident about wanting to move to, it may not be a bad idea to find a room/apartment as a "zwischenmieter", so that you are then in the city while you are searching. I think that can make a big difference in what you find as well as your likelihood of getting the apartment.