Google Nexus 4 — Kit kat update messed up my phone

Help please my phone recently updated to Kit Kat and now my phone is a mess. When I go to contacts to make a call the screen goes black makes the cal but you can't get the scream to come back. It stays black and I keep trying to get the scream back and it flashes when I can finally get it to show the screen it wants to shut down the phone. I am diabetic and have a bad heart so I need to be able to call my doctor or the hospital and with it doing this I can't always get the people I need to contact specially when it asks me to press a number and I don't have a screen to see. Is it possible to either roll back my phone to jelly bean or is there a fix expected for this problem? I really am at my wits end with this because my phone is necessary for health reasons. Any help will be greatly appreciated. I don't even know how to contact google about this issue because I can't find who to tell. Thanks so much Marie