Need advice on medical debt.

I just got off the phone with my hospital billing department. 6 months ago I set up a payment plant of $25 a month. I received a letter in the mail last week saying my account was reviewed and now I need to pay more. They want me to pay $180 a month, which is not possible with my income. The representative then said she would look and see if I was eligible for any charity, which I was eligible for 60% pay off if I agreed to pay $80 a month, which is still not doable for me. I told her this, and she said "fine then you're just going to get sent to collections". I could probably afford maybe $40 a month, but that is really pushing it. I don't want this to go to collections as I am slowly trying to rebuild my credit. I've got credit cards, student loans, and a car payment ( I made many poor decisions when I was younger). On top of all of that, I am currently out of work because I had surgery last week. I'll be going back to work in a week, but it will be light duty and I won't be getting paid the same (I work nights normally and get a 15% shift differential, which I won't be getting while on light duty since I'll be working days). Any other suggestions I could try?