Was taking metronidazole for bacterial vaginosis but it caused severe itching and a foul odour. does it mean i have a yeast fungal infection instead?

Maybe, probably not: Yeast infections cause itching but usually not odor. Probably the odor is from the BV itself, even if first noticed after starting treatment. But regardless of odor, the itching could indicate a yeast infection. Allergy to metronidazole unlikely but possible. You also need to be checked for other STDs like gonorrhea, chlamydia, and trichomonas if not yet done. Discuss with your doctor or clinic.