How do you know if your LO might have an ear infection?

DD has had a cough for a week now. She had been sleeping okay but now we're on night two of crap sleep. She'll cough and wake up. She'll cry and not be consoled. She'll be asleep and wake up as soon as she's put down. Last night was every 2 hours until we put her in the swing. Tonight she lasted about 2 hours and I can see how it's going so she's in the swing already... I just wonder if I should be calling the pediatrician at this point. My MIL said frequent wake ups when laid down can be an ear infection sign so I'm worried now. She acts fine during the day and naps on her belly at daycare. It's just the overnight that has me concerned now. And I'm sick too so this isn't helping...