OK, sweetie, first of all, you probably bonked your cervix with the end of the hairbrush. Guess I will mention although you shouldn't need to hear it, don't use a hairbrush to masturbate. Nor a toothbrush, nor an electric-toothbrush body. These things are not for the tender internal tissues in a vagina and at the end of your uterus, which is what the cervix is. Also, don't use a bottle with the open end pointed towards you, it can cause a vacuum that can actually tear your support muscles and pull your uterus forward, like a uterine prolapse. In short, don't use something to masturbate with that's not safe, and get educated on what is safe.
So, smooth, not-hollow things are safe, if they are not longer than your vagina, and a certain amount of flexibility is helpful because the vagina is not entirely straight, there's a ridge in the top that can get in the way.
But besides the puzzle of which household object can safely go into your body, seriously, if you have any way to buy one (Amazon, or a woman's bookstore), get a "toy." There are ones not designed to look like a penis that are for stimulating your clitoris without the need for penetration, I've heard the "Pocket Rocket" is really good and does the trick no muss no fuss. Also one more shaped like a woman's body (although a bit penis-like) is called a "Rabbit." A woman's bookstore in my town has a basket of Pocket Rockets right by the cash register -- they obviously don't think it's anything to be embarrassed about! Safe orgasms are great.
Also, if you are massaging from the outside (which works fine for clitoral stimulation), you can even use the kind of massager they sell at Walgreen's in a box with a picture of a smiling person massaging their neck or shoulder. I guess some people do buy these for general muscle massage, though I've never used mine on my neck. lol
Anyway, it's not deep penetration that gives the biggest bang for your buck, the back third of your vagina has no nerves anyway so can't even feel the hairbrush handle. What brings on the orgasm is the stretching of the muscles at the mouth of the vagina, and some also say the pressing of the "G spot," which is not very far in, and the pressing on the clitoris, which is also positioned at the mouth of the vagina. It's not like you even needed to go deep with your hairbrush, it is probably more likely you needed to go wide, and some pressure.
Good luck, and no more pounding your defenseless cervix with a hard object. Especially at mid-cycle when it is ovulating (which is the most common time for a woman to feel horny), it is sensitive and hangs lower, and you just don't want to hit it with something hard.