A word to describe a person that is solely responsible for all of the problems (like "causer" but not exactly)

Question

I'm looking for an English word I knew beforehand but now I've forgotten!

The root of the word pertains to the word "cause". It's also a noun that refers to "persons".

Let's look upon it, as an example:

You tell a someone: You're the causer of all of these problems. ("causer" is not the word I'm looking for, but close to it and with the same meaning)

Actually, we use that noun to say the reason for the problems is that person solely, and he is guilty/responsible for all of them.

The synonym names close to it are: Cause, responsible, reason and son on.
Now do you know what word it was, please?

If you mention it, I'll quickly recall it.

Answer 1

Typically when people say "You're the x of all of these problems", the x is typically "root"

root

You're the root of all of these problems.

the source or origin of a thing: The love of money is the root of all evil. (definition 7)

Alternatively, you could be referring to "origin","source", or "mastermind"

Answer 2

The word you may be looking for to call the person who causes all your bad problems is

jinx

He is a jinx to us and everyone he meets.

Answer 3

One word that fits the bill is "culprit." Other words are "cause" or "source." It is perfectly good English to say "You are the cause of these problems." A phrase that works is "you are to blame."