Hi Zach,
It has only been 3 days. Try not to panic quite yet.
She may have gotten so used to the fact that you are usually the one who initiates conversations on messenger that she is waiting on you to do so again.
Give it another day or two to see if she initiates. If she doesn’t, it may be best for you to start a new conversation with her and ask her if she has a boyfriend or someone else that she is seriously talking to with strong romantic potential.
If your ultimate goal is to become romantic with her, you need to make sure that she is available to you for that.
Otherwise, you could spend another 2 weeks or more initiating the majority of conversations with her with nonstop texts and be simply wasting your time.