If it's any consolation, I was about to post a thread for the very same reason. I have a 14 month old DS who has, this past couple of weeks, started getting VERY clingy and throwing tantrums, during which he doesn't know whether he wants comfort or to push me away.
He started nursery one day a week a month ago, and each time has come back with a new virus, as expected. However, one was particularly nasty and landed him in hospital for a week (he had a very high fever for nearly 2 weeks), and recently we had to go away and stay in a hotel for 4 days while I took a course (of course he came with us). Not surprisingly, since then his sleeping has been messed up - he won't contemplate going in his cot, and actually wants to be rocked to sleep in my arms, which I am doing at the moment as I'm going to wait until he's feeling confident again before trying to get him to sleep in his cot. Makes naptimes and bedtime difficult though. He wakes up in the night reaching reaching out for me and then crawls over until he is nestled in my arms.
The tantrums are new - he's very strong and arches his back and it's difficult to do anything with him, especially try putting him in his buggy. When in a tantrum, his hands are often in his mouth which makes me suspect teething pain as well.
He has also had to miss his immunisations due to continuing illness. He still needs his booster and MMR.
Eating has gone to pot - he wants snacky things (especially baby biscuits, which were the only things he'd eat when ill) but has suddenly got very picky and often rejects main meals.
He also has eczema; ditto the Epaderm and Oilatum. The former works better than the latter but the eczema still keeps coming, and recently I've noted DS pulling at his clothes as if he's itching (before this, it never seemed to bother him, but just looked unsightly)
I've probably bored you with all this, but just wanted you to know you aren't alone - sounds like your DD and my DS are very similar! I'm sure things will improve. I wonder if your DD had a similar virus to my DS and it has just taken her a long while to get over it?