Default [Q] nexus 5 touch screen freeze/autonomous touch screen problem

i have got my nexus 5 in november..for a month i dont have any problem..
10 days before i had a problem..touch scren frezzes..few minutes it did not dont work and for few min right haolf was not working and left half was working..for few min it was working only if i press not with fine touch..for few min it was someone is keep on pressing some buttons..then after an hour it was fine..

and again after 10days,yesterday, i had such problem lasting for 15min to 2 hours ..since yesterday on & off similar problem with my nexus 4..and at present it did not correct till now since yesterday...i tried safe mode too..left half of screen touch is working, righthalf is works for hard press and swiping pages not for opening any thning or fine functions..

i noticed it was after updating to 4.4.2..may be coincidence..plz do the needful.......

my friend has gifted me from us..i m i m in trouble..wht to it software or hardware problem?