I got really curious if there's a manga out there with a character with tourettes or other...

Ff

I would recommend http://www.mangago.zone/read-manga/isso_koe_ga_nakattara/.
Not really a syndrom, but the mc stutters, so maybe it still fits what you are looking for.
The struggle is really well described. (Both from the side of the mc and from his bf, who tries to understand and support him)

Thank youuu