In desperate need of advice!

My daughter will turn 7 months next Tuesday! She already has 3 bottom teeth and was very chill about it when they all came out. In general,  she's a chill baby and rarely cries. However, last night we couldn't get her to sleep till 2 am when she's usually asleep by 9 pm and sleeps through the night. She was totally fine during the day and for most of the night; we couldn't get her to sleep but she wasn't too fussy either. She is coughing and congested though; my mom noticed that her gums are red and that she is constantly looking as if she is chewing her gums and has a hard time taking her bottle. She fell asleep at 2 and woke up at 5 am, we tried giving her bottle but she was very fussy for about 40 minutes. I put her down at 6 am and she had no problem falling asleep until about 7 am. She started all over again but it has been off and on. There are moments where she's quiet and chill and then she'll start crying again. We gave her Tylenol around 1:30 am and that seemed to help.