Yes, you can.
Yes. It sucks. Ouch. :( But unfortunately, you probably can't effectively use the treatment creams until your period is over, if you prefer to use tampons. If your period is light enough to used a pad overnight then you can start the treatment. Good luck. :)
Answer Yes, it's very common. When you get a yeast infection, when you are having your period it's because the ph-value changes. and that makes perfect conditions for the yeast, to grow ..You can start treatment whenever you like - you can get pills to take, orally and vaginal. I'd say the vaginal works faster, and better. If you take them before you go to bed, there shouldn't be any uncomfortable problems :)
Answer Unfortunately, hormonal changes, such as those that occur during the monthly cycle can be a significant factor in causing yeast infections.