My baby girl is 3 months on the 17th and shes always been a great sleeper at night we went from waking up 2times too 1 time and then none!

But out of no where these past couple nights shes easy to get to sleep but as soon as shes put in her cot shes waking up every 20/30mins and we are struggling to help her settle, she wakes up screaming but as soon as shes picked up she stops and falls asleep again just dont know whats best to do for her!

Any ideas on what could be causing it?