First of all, don't stop breastfeeding over this - your hair loss has *nothing* to do with whether or not you are breastfeeding, it's all about the fact that you are no longer pregnant.
Apparently, the hormones that we produce while we're enceinte keep us from losing any hair during that 9 months, and as they leave our system, the hair from that whole time starts falling out - all at once. Since on a normal basis we only lose a couple hairs per day, as they fall out/grow back it is less noticable - but when we lose big clumps after pregnancy, we really notice it! Since the new hair starts growing as soon as the old one falls out, you still have the hair follicles, your hair just has to grow long enough for you to see it. (If you get pregnant again, you'll have another nine months of growth without any falling out, so you won't go bald. =- )
I have really healthy thick hair too, and I lost so much after my 2nd daughter was born last September that I was getting really worried and talked to my ob/gyn about it. I lost a bunch after my first was born, but nothing like this!
Anyways, she said hair loss generally continues until month 6, then it stops. If it continued past 6 months, then she would give me a referral to a dermatologist.
Well, I hit the 6 month mark and like magic, it stopped - one day I had another handful come out in the shower, the next, nothing. My daughter just turned a year and my hair is almost back to normal - I cut my hair a bit shorter to help blend in with the stuff growing back, mostly because I lost a big patch just past my left temple and it seemed really obvious to me. It's still not all one length, but that will come with time as it grows back.
So, looks like you have another 1-2 months of hair loss left = ( but it *will* grow back. This is what I would do: If it doesn't stop during the 6 month mark get a referral to a dermatologist. Keep taking your prenatals (you should be anyways since you are breastfeeding), they are a complete vitamin source. In the meantime, wear a hat to cover your scalp (too much sun might be drying it out and causing the itch), switch from ponytails to headbands or clips (less stress on your hair), and look at your conditioner/shampoo combo to see if you should be using something more moisturizing.
Good luck!