I need the Hives help!

Background: I have been spoiled with DD's sleep. From Day 1 I tried hard to get her good at putting her self to sleep and back to sleep. Minus a few hiccups (which I think are normal growth/development stages) she has STTN since about 6 mos old. I always lay her down grogy and she falls asleep on her own. Sometimes she lays in her crib for 30-60 mins just doing whatever and sometimes she chills out in the AM before waking me.

Now: She will be 2 on Saturday. Her usual (since say 9ish months) routine is sleeping 7pm - anywhere between 6 & 7am. Usually 6:30am. Its great. Around 6:30 we usually stop "playing" and start winding down - which does often include a show/movie. At 6:45ish we go upstairs - diaper, clean up, jammies, bottle, book - then to bed. (Side Note: I know I need to drop the bottle and switch to a sippy of milk - its on the list).

Recently: Starting this weekend a couple nights in a row she was waking early (like 3am/4am) crying and when I'd go in she'd say "all done nigh nigh". I'd tell her "no - its still nigh nigh, please lay down and I'll tuck you in". Over the weekend she agreed but would wake constantly after that (like every hour). Then I noticed Sunday she was getting congested - I'm thinking maybe allergies. No fever, appetite has been fine. Sleep at Daycare has been fine. Tuesday night was a MESS. 7pm-9pm a mixture of screaming hysterically, thrusting herself around her crib, hyperventilating and just generally acting like a demon. We could not get her to go to sleep. Finally I set up the pack n play in our room and she laid down after 10 mins of crying in it. Slept from 9-6am. Last night, after some suggestions from friends, I tried giving her benadryl for the congestion. She went to sleep on her normal routine (in her crib) and slept 7pm-5am. At 5am, she refused to go back to bed and insisted "all done nigh nigh".

So - I am wondering, do you all think this is a growth spurt/development phase she will break out of? Is it related to her cold/allergies? DH will not do a cry it out method while she is under the weather - so I am terrified of creating a bad habit as we go through this transition.

Thoughts?