I have something to add onto the comb question...what kind of comb did you use?
Because if you used just a wide tooth comb, then it's possible that you didn't get all the shed hairs out, which could have contributed to the matting. I don't wear braids anymore, but when I wash now, I comb my hair first with a wide tooth comb, and then I follow up in small sections with a fine tooth comb. The wide tooth comb detangles hair, and the fine tooth comb removes the shed hairs, which means a tangle-free wash for me. If you didn't go back through with a fine tooth comb, I'd say that there were still sheds left in your hair that matted and tangled up when you washed.
I'm sorry you had this experience though...wishing your hair a speedy recovery!