my generic Teva backordered... they're offering me Solco at CVS

I've only used Teva since I started Jan 2nd and concerned.... but no one else seems to have it in stock either....

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I called Teva and they said it might be in stock end of month.

Called CVS.... they said they'd heard it would be available before now... and they have other Teva product that was supposed to be available a year ago...

I have a little time before need so hoping it will be available in another week or two.

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If I end up having to switch how long should I give for the crossover?