GPs should know about clonodine. It's a blood pressure medicine that counteracts the massive norepinephrine dump you experience when you kick (and which is the number one thing that makes it so unbearable). It helps a lot.
Besides methadone there's also buprenorphine and Suboxone, which are opiate replacements. Not the kind of thing you take to get high, something to use to taper off so the withdrawals aren't so intense.
Heroin abuse is a big problem that's only going to get bigger in the US. A lot of folks got addicted back when Purdue was pushing Oxycontin, and now that it's harder for them to obtain they've switched to the cheaper and more potent stuff.
Doctors need to know how to treat withdrawal, period. There are lots of options besides methadone (which has it's own nightmare withdrawal if stopped abruptly, and which lasts three times longer than heroin withdrawal).