Try to keep flat ironing to a minimum and be extra careful when taking out your clip ins so that you're not pulling out your hair. Also, if your clip ins are heavy then the strain on your scalp may be causing your hair to weaken and fall out.
You may need to start using a conditioning hair treatment to bring your hair back to health. Check out the Pro Naturals Moroccan Argan oil Treatment kit or at least the Argan oil on its own. They can revive your hair and keep it healthy, plus they also prevent hair loss and stimulate hair growth.