Help with my 7month old?

i really need some help...my 7 month old boy has changed over the last few weeks..he wakes up through the night when before he was sleepin 8 till 7. he wakes up screamin and most of the time wont go back off on his own.hes now waking up at 6 and wont go back to sleep.im knackered and to make it worse most of the day hes cryin to for no reason..he wakes up from naps cryin and is being really clingy towards me...dont get me wrong i love the fact that he wants me but its so tiring.i took him to the doctors about a rash and he gave me some cream said that might be whys hes not sleeping but its made no difference..i want to enjoy being a mum help!!!!