Hello, I've always been tired of a question. Suppose a person learns medicine, but is also interested in many other topics. Reads texts related to physics, astrology and geology. And my question is this. Can the brain be tired from the information overload? Can a large amount of information provided to the brain cause that we will start to forget things previously remembered? Will the brain make free space for new information in such cases? Thank you very much for any answer.

Yes, you will forget stuff.  For instance you might forget that astrology is not astronomy.

The brain has it's limitations just like everything else. But there impressive nonetheless. 

Quote

The human brain may be able to hold as much information in its memory as is contained on the entire Internet, new research suggests.

Researchers discovered that, unlike a classical computer that codes information as 0s and 1s, a brain cell uses 26 different ways to code its "bits." They calculated that the brain could store 1 petabyte (or a quadrillion bytes) of information.

https://www.livescience.com/53751-brain-could-store-internet.html