2 days into flowering and somethings wrong!! please help

well i have been vegging for 5 weeks now and everything is awesome. i have four plants under 1000 watt mh, so they are pretty big. let me start by saying that i have them under mh right now,but on flowering schedule.(12/12) i am gonna get a conversion bulb soon to run hps in my mh system(cash is low right now)since cash is low and plants are too big i had to start flowering and since two days all the branches are falling down and turning sideways. Any suggestions????

you'd need to post some pictures for an accurate diagnosis

pics please. have you thought of topping? or maybe LST....

Sounds to me that the plants have not had enough stimulation from the wind leaving them with weak thin branches,do you have a fan blowing on them,if so does the fan make the plants & all the branches move ?