what do you all think?

here`s the deal:
I have had lots of severe health problems lately and it has shown up horribly on my hair- it breaks very easily and nothing i`m doing- deep conditioning, being extremely gentle- is making it any better(i suppose putting conditioner on the outer parts of your hair isn`t going to help when your hair is unhealthy from the inside anyways.)
The thing is that before i was diagnosed i noticed my hair getting bad and so i cut it off- it was pretty long and i cut it to my chin. I immediately started growing it back but it came in very unhealthy. Now, it has grown to a couple inches below my collarbone.
What does anyone think: Should i cut it off again and then regrow it(hopefully it would come back better looking now that my disease is more under control) or should i leave it longer and just trim off the unhealthy stuff as it grows? Do you think either of these would work better or be better for my hair?
I`m also taking biotin to try to make my hair grow in a little stronger. Does anyone have any suggestions for other single vitamins- not specifically hair vitamins/multi vitamins though-that would make hair stronger or grow faster?
Thanks and sorry this is so long:)

I have very long brunette hair past my waist, and it is healthy, but I like the look of short styles so much I am considering going to a very cute short style.If you cut your hair much shorter it might look good and be good for your hair too!