Collect half rent?

[Christian Bors]

So I have a tenant who sent me a text message asking if she could pay $300 dollars now, and another $ 300 on the 16th plus the 25$ late fee.  I inherited the tenant over a year ago and she has been very good.  Hasn't complained, and besides one other late payment (last December) she's been great.  However, I am starting to get worried.  What should I do?  If she gets paid on the 16th, the following pay day will be the 30th.  So she will owe another 600 which I'm assuming would be the majority if not all of her paycheck.  What does BP recommend?  Thanks in advance.