Help!!

My 14 month old is going through major changes at the moment. She keeps getting very stressed out over little things and is waking at 4am every night screaming. She sometimes screams in the same way in the day as if she’s annoyed and nothing can comfort her. At a loss on what to do and I’m not sure why this is happening. Feel useless when I can’t even comfort her. Changed her nap from one to two as she was only sleeping 40 mins at a time throughout the day so put it down to being tired but just have no idea. Anyone been through anything similar / have any ideas on what it could be and what I could do to help? Any suggestions welcome thank you in advance!