Lazy eye in 18 month old??

Ok. I’m currently in Italy about to head back home after a two week vacation. My daughter has been having her eye lid seem like it gets stuck down sometimes or is becoming lazy. It only happens once in a while and seems to be happening more now. I’m wondering if it could be because she’s tired. Her naps haven’t been as long during the day. It’s strange how it will close a little while the other one is still wide open. It sometimes takes a second for it to open to the width of the other eye. I’m wondering if anyone else has had this problem and what was wrong? I’m really worried and I’m absolutely going to be taking her in as soon as we get home and I. CAn get an appointment. We head back tomorrow but of course I’m still worried.