my usually great sleeper is having trouble! for the past week or so, she has been waking every night at about 1 am. a couple of times, she just cried lightly on and off for about 30 mins. enough to keep me up, but i didn't have to go in. but some nights, she starts off crying lightly, then starts crying hard, so i go in and pick her up. once i pick her up, she is mostly asleep, her eyes are closed, but flutter open occasionally. she flips and flops around in my arms until i think she is uncomfortable, so i put her back down. then she starts crying lightly, then hard, so i pick up again...repeat. this has gone on for up to 1.5 hours.
there have been no changes in her schedule or diet, no milestones. anyone have any idea what this may be? am i handling it appropriately? i want to comfort her if she needs it, but don't want to create a new bad habit. TIA.