Overtired, Then Sleep

Major sleep issues. Holy cow. C has always been one to wake up in the night and she has always been relatively easy to put back down. For the past two nights (this, by the way comes after several nights of solid sleeping through the night) she has been waking up every 1-2 hours until about 4am at which time she sleeps to about 7am. The wake ups would be manageable if she were easy to put down. She's not. She clings. She falls asleep in my arms and then wakes up the moment her bum touches her crib. [She has always slept best in her crib]. Last night we were up from 12:15 to 2:30 straight. During the day her napping has been getting progessively worse. Short naps. Single naps. Fighting naps. I have a feeling she is overtired at night. Overtired is a concept I can't get my head around. I mean, if you are tired you should sleep. But I guess in baby-land it doesn't work that way. At least, this is my theory. Crappy naps during the day are leading to several clingy wake-ups in the night. So today I am trying to get her to nap. And she is fighting it. I feel awful because I am feeling the effects of being up for 2+ hours in the night. She was crying in my arms at one point and I couldn't help but start crying too. There could be other issues here too. She is learning a lot during the day and this could be affecting her at night. She still only has 2 bottom teeth but very swollen upper gums (so, teething is a serious possibility). I don't know. But it sucks to cry.