If i'm resistant to metronidazole for bv does that mean i'm resistant to tinidazole as well?

Probably not: although the are in the same family they are slightly different chemical compounds and not the same so the other may work.

Probably: since it is an expensive version of metronidazole it probably will not work. Sometimes a different delivery form can work even with the same medication You need to see a provider and have a culture done and see if they is one medication which would help you and make sure it is not a yeast