9mo ds was a very difficult sleeper for the first 3 months. Then was a total dream even though he needed held to sleep, we could still put him down and he'd sleep through the night. We sleep trained when the 4 month regression hit and he was falling asleep on his own fine, and sleeping from 8.30-7.30 every night. The last few weeks he will only fall asleep if held, most of the time he can't be put down at all or he wakes up. Even at that he needs almost actually restrained to hold him to sleep as he still screams and kicks and punches. Have tried sleep training again, even leaving him to cry but the longest I've managed to let him cry (whilst going in every 10-15 mins for reassuramce) is over an hour and hes still wide awake. Night time sleep is completely out the window and I'm exhausted. Any advice?