Looks like my little brother is swinging toward mania | How can I help?

I have a brother who is living with bipolar disorder (not sure of the PC way to say this... apologies if I am wrong). He tends to go through the typical swings of mania and depression. He's in his mid-20's and largely has balanced his bipolar disorder through natural meds and "self-talk" (I know, not perfect, but, he eschews the idea of a therapist). Our family is very supportive - but he has cut some out and has in the past disappeared from even our mom for months.

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I think he he is swinging toward a manic phase. He's changed jobs about three times in five months, now at his new job he thinks two colleagues hate him, he's only a month into his job and planning to submit a business proposal to his boss that involves radically changing the business he owns (I tried to tell him it's too soon... be does not believe it), and he had an unusually explosive blowout argument with one of my siblings. Plus it's the holidays, he just moved into a house where shares with an elderly woman, and there is relationship stress.

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Any ideas for support or helping him? He came to me for advice on the proposal and I noticed he totally disregarded that - so I can tell he's not listening. I've thought about flying up to him so he sees he is a priority (he is in NYC so I can couch it as a holiday city trip / see him). I think trying to get him into therapy is beating a dead horse. I am totally at a loss.