JM 30DS Tightness

I posted this in my JM group, but havent gotten any responses yet so I thought i would try here.

Hey so I have a question, that maybe a bit TMI. I jog and walk when I can and do several dif. cardio workout tapes and I am always able to stretch well. But after 30DS i have a lot of tightness in my groin/lower pelvic area. I usually can do the groin stretch where you bring the soles of your feet together as far up as you can and gently press your knees down while you bend. Normally I can bend to the floor, but after this work out I can barely get my feet together let alone bend with out pain. I am curious if I am doing something wrong in the plank position. Maybe holding my weight incorrectly. Has anyone else had this problem? Or maybe just have some advice for better form? Thanks.