Does learning a forth language confuses your third language?

Chinese is my third language. The first time I pronounced a Chinese word was five years a go. Now I speak it fluently at business level (but unfortunately I can’t read or write the characters). It is a wide language, and I am still learning new things everyday...

I started learning German two months a go. It’s going very well so far. Anyhow, that’s not the point. What I noticed lately about my Chinese is that the words or expressions that I don’t use frequently, I find myself having some difficult to spoke them out as fluently as it used to be before. I thought maybe this is because my mind is driven now to focus on German, and that may cause some sort of confusion in the learning process.

Has anyone had this kind of thing happened to him/her? Is there a limit on how many languages we can handle in our Brain cells?

Certainly there is a limit. Your brain's obviously only has a finite capacity. However, since there are some people that have learned over 10 languages, I think you should be able to handle 5. But, it may be that you are using time that you previously used to improve your Chinese to work on German instead, and because of that, you are losing some of your ability. The less you use a language, the harder it becomes for you to speak it. This is true even for native speakers. A native speaker of a language can easily forget vocabulary words that they don't use often.

Quite true, especially for languages as different as German and CHiense.

It's actually harder when it's two similar languages like French and Spanish. With two vastly different languages like German and Chinese, I don't think it would be too easy to mix up words and phrases.

IT happened to me with English and French. for example marriage and mariage. But i think is normal, you just have to adapt your brain, at first its hard but later there is no problem.