hair falling out in clumps is usually caused by some sort of allergy , to either medications or enviroment , if it falls out all over this is usually a hormone imbalance , women going through menopause will start to thin out due to estrogen levels dropping and testosterone levels increasing and converting to dihydrotestosterone or dht which most men with male pattern baldness suffer from the good news is that the spikes means that new hair is growing back to replace the old hair that fell out