Baby won’t sleep

My baby is six weeks old and has a pretty regular sleep and nap schedule. Today, she woke up from her nap at 4:25pm and HAS NOT GONE BACK TO SLEEP!!! I’m currently nursing her (it’s now last midnight) and I can’t get her to sleep.

She’s been nursing almost constantly since she woke up and she will nurse herself to sleep for all of five minutes and then wake up again. In between nursing, all she will do is cry.

I’ve given her gas drops, she has a clean diaper, I’ve been burping her... I don’t know what to do. I’m in tears. I’m exhausted and I can’t get her to sleep.

She’s never been awake for more than a few hours at a time. What is going on!?!