My 5 week old suddenly won't sleep anymore unless being held entire time!!!!!?

i've talked to sleep specialists about this, and they said starting at 6-8 weeks, is when the baby will develope the normal sleep schedule he/she will keep until it's old enough to sleep through the night and on their own.. She said to make sure baby is fed/warm/safe.. then cradle baby/rock her back and forth... until she's almost asleep.. but still awake enough, lay her down and let her go to sleep herself.. even if she cries for a little bit (not saying long!) she will develop a sleep pattern of putting herself to sleep.