According to what I found here I’d translate to: “frénétique” or “intense”

A few words exist :

Mouvementé

Can refer to what you mean, can be quite pejorative.

Agité

But it’s difficult to replace ‘hectic’ directly with ‘agité’, you would have to change the whole expression for it to fit.

Trépidant

Not especially pejorative, this is what I would use instead, unless you want it to be pejorative ; in that case, consider using ‘mouvementé’.

Context: talking about a very agitated period of s.o.’s life, possibly a bad one.

You can use « mouvementé » then. This is the most appropriate word French speakers would use. For instance : « une période mouvementée » (when refering to someone’s life).

Although “tumultueux/euse” is probably used more often to describe such years or eras in world history or to describe someone’s entire life (as in the title of this film) than it is to describe a particular part of someone’s life, this entry from Word Reference makes a connection between that French adjective and hectic:

tumultueux adj littéraire (riche en événements)

tumultuous, eventful adj
hectic, turbulent adj

(here’s another link to the film mentioned above which translates the original French title, La tumultueuse vie d’un déflaté, to The Hectic Life of a Dismissed Worker in English)

I think “maniaque” would match your description.