Took 250 2 a day for 7 days of metronidazole for BV didn't work then 500 2 a day didn't finish course. Should I take another course In a few weeks?

No. You should speak to a doctor about this before taking more antibiotics as prescribed. How do you still have so many antibiotics left? Are you still having symptoms? It is best to be re-evaluated by a doctor before trying another course of antibiotics. There are always potential side effects and you could build resistance if you take antibiotics you don't need. Best wishes.
Treatment. See you doctor and have a culture and sensitivty of your vaginal infection. It appears that Flagyl is not working.
Cream. Sometimes a course of potent antibiotic vaginal cream is also needed to clear a bacterial vaginal infection. Discuss this with your gynecologist.
You may need to . be tested again. Do you have symptoms? Have you tried taking probiotics? You risk getting have severe heartburn/stomach upset after all that Flagyl. Consult your GYN provider,