Drugs like amphetamines can in some cases worsen existing mania, or bring it out in people predisposed to becoming manic; these drugs an also mimic the symptoms of a manic episode if taken in a great enough quantity (less need for sleep, racing thoughts, sometimes even psychosis, etc.), so what you've been experiencing could be caused by any number of things. It's really a good step that you've decided to quit using right now, and you've told yourself and written it on this forum (it might not seem like much, but a small commitment can be made by writing it down). I don't know too much else about the drug effects, so I'm not sure what could be happening when it starts to work against you. It could be a rebound effect from taking high doses over an extended period. Like Xila mentioned, there is an addiction forum, and perhaps there are some people who could help answer that part of the question a little better.
As for your daughter, her behavior and mood sound troubling and serious, but she will need to get evaluated by a professional to know for sure what is going on. It could potentially be some form of a manic or mixed episode, or it could be depression (irritability and paranoia can be common symptoms in depression as well as mania). Mood disorders can be complicated, but they can also be treated. Whatever is going on, it sounds like it's worth speaking with someone about, even a counselor if one is available for the time being. In the meantime, make sure to check out the websites posted in the "welcome" post at the top of the forum if you haven't already, just to get an idea of what one might see in a manic or hypomanic episode, and you can compare that to what you and your daughter are going through.
http://www.medhelp.org/health_pages/Mental-Health/Useful-Bipolar--Depression-Webisites/show/523?cid=105