Im a nutritional therapist and a candida survivor wanted to give you some advice.
Firstly, the birth control pill can increase oestrogen, or cause hormone imbalance- which in turn causes copper toxicity. Copper toxicity causes candida. Balancing copper dysregulation is the cure for candida. Heres my blog article on this: http://sarathackeray.com/2016/10/30/cause-of-candidiasis/
That doesnt mean you need to stop the BCPs right away, but you want to start addressing copper dysregulation in the body. When i did this i cured my candida.
After addressing copper dysregulation with HTMA/mineral balancing your period pains may also improve and you can come off it.
Also you need to find out the cause for why you have such bad period pains. Is it PCOS, edometiosis? All can be addressed naturally by balancing hormones etc. Then you will be able to reduce the pain.