Any chance it was just due to it being your ovulation time? I know I tend to get a discharge around that time that I would describe the same way you have.
Hi,
Well if it's not a yeast infection, not cottage cheese like, doesn't have an odor or off color such as green or yellow, it could just be an increase in discharge if it's before your period.
If there is a chance you are pregnant, it could be that the exercising caused an increase of estrogen (sp?) production and blood flow to the vagina.
Sometimes though, those large lumps of white discharge can be an indicate infection. If it continues, I'd say to have it checked out. Good luck to you :)