About losing your language

Sometimes it feels like I am losing the ability to express myself in my mother tongue. It is a strange feeling. As if my synapses aren’t working properly anymore. As if I lost all my thoughts. 
When I am trying to write E-Mails in German, I don’t know how to say things. How to form my messed-up thoughts into proper sentences. How grammar works. (And let’s not even start talking about proverbs and sayings…) The problem is, I also still struggle with English and though I’m understanding most things and I actually feel almost fluent at it, I still make tons of mistakes and I’m still lacking so much vocabulary that I don’t know where to begin… So my linguistic skills are fading away and I feel like I am robbed of something I always considered crucial to my character. Being able to master the (german) language, being able to write and express myself, being a painter with words - yeah, that was how I saw myself for a long time. Or at least for some moments. And now? Now I feel like my thoughts have dyslexia or something… In both languages. (And I know that there is a better way to express this, but the words escape me). My brain is mutilated and I don’t know how this could happen. I am lacking a crucial part of myself and so far it doesn’t seem like I will get it back… Maybe multilinguality is not for everyone. Or maybe I am not what I thought I am. Maybe my skills are lying somewhere else…