If you truly think that rehab would be your best bet, then don't hesitate calling the state you live in and ask for assistance. Also, call individual rehabs, tell them your situation, and ask for help or a referral. You'd be surprised at how much help will be offered if you ask for it.
I think 95% of the members here know what you mean in the thought that Rehab is sort of out of the question -- but do you have any options to where you're able to go to a doctor for help with this? If not, then I do know that there are other members here who've had experiences with heroin and cocaine usage. My DOC was percocet, so I am not sure how well I'd be able to help you out; But I hope that some of what I've told you helps!
My heart goes out to you. Unfortunately, it happens. Do not beat yourself up. What did you do to get clean before? Rehab might now be necessary considering you already did this before. Just do what you did there at home with the aid of friends or family. Spend a lot of time getting support on this site. You must know that the detox will be rough. But you will live.
I suggest you might see a doctor to assist you if you cannot affor rehab. The detox might not be too severe since it has only been a month. call your doc. Let us know.
Good luck and keep posting.
Matt