I have had it on and off for the past three years.
这样断断续续地有三年了

on and off
断断续续
It rained on and off for the whole afternoon.
雨断断续续下了一下午。

A:What seems to be the problem?
哪里不舒服？
B:My stomach hurts,Doctor.
我胃疼，医生。
A:Has this been a problem before?
以前有过这样的问题吗？
B:Yes.
有过。
A:For how long?
多久了？
B:I have had it on and off for the past three years.It's just got much worse these past two weeks.
这样断断续续地有三年了。只是过去这两个星期以来疼得比较厉害了。
A:Do you only feel this way when your stomach is empty?
您是只有在胃空的时候才有这种感觉吗？
B:After I've eaten,it goes away for a while.
吃了东西以后，疼痛会消失一会。
A:Do you feel nauseous?
您感到恶心吗？
B:Yes,occasionally.
是的，偶尔。
A:Let me take a look at your abdomen.Lie down on your back and bend your knees up.Ok,relax...Alright,it seems like you have a duodenal ulcer,but we'll have to run some tests before I can be certain.You should get a good rest first and try not to strain your stomach too much.
我来检查一下您的腹部。仰着躺下，把腿蜷起来。好的，放松...好了，看上去好像是十二指肠溃疡，不过我们需要做一些化验才能确诊。您首先应该好好休息，尽量减轻胃的负担。
B:Is it serious?
严重吗？
A:Not too serious,but it'll take you some time to recover,so you'll need to be patient.
不太严重，但得一段时间才能康复，所以您要耐心点。