This is bad. Seaturtle is on the right track. You should go that route. I know in certain states if you have a low enough income you can qualify for a States secondary insurance. In California isn't called MediCal. It won't be quick enough for you, BUT, as in the case with MediCal you can pay out of pocket and they will cover the med retroactive up to 3 months. What you have to do with MediCal is go, qualify based on income usually, and rush the process by stating MEDICAL NECESSITY. On the forms mental illness is clearly listed. And then the process starts and can take up to a month. BUT if you go to EPS (or the like where you are) Emergency Psychiatric Services (which is part of the county health system) and they are required to help with temporary meds if it proves necssarry. They will diagnose and you will get help. I know. I've done it myself for others, and had it done for others who probably would let me do it

-- like my friend. And you can get the Lamictal through them. They will want to know your income level and they will bill you if you don't get the state supplemental insurance (like MediCal). BUT, as I said in the case of MediCal ONCE you are approved, you can get paid back retroactive up to 3 months, you just prove you are going through the process when you are treated. NOW...IF you are denied, in the case of MediCal and the county system in a state like California, THEN you go and SHOW them the denial letter. And in that case they usually waive existing balance/fees and you continue from that point at a reduced cost, based on income, but it will be out of pocket.
In any case I advise contacting the county health system in your area, explaining your situation asap and going that route. Then get supplemental insurance through your state or county, IF they offer it.
If all this seems daunting then contact **** (just do a search on "****" in your state and area (they ARE nation wide). Print off what I have said, read it to them and ask them if you have anything similar in your area. I'm SURE they know and can advise a emergency solution. They are there for exactly this and more. I'd be surprised, if you live in a metro area if they didn't have a EPS (Emergency Psychiatric Services) of some sort for you to go to. Just know that it is usually a lock down facility and they can hold you for 24-72 hours IF you are a danger to yourself or others.
Please let us know how it goes.