When would a simple cold turn into flu & is it more then just pre pms..ive have a cold for 4-5 days. this am i woke & had diarrhea, vomiting & chills.

Doesn't 'become' one: A cold will last about a week, so you're not past the avg time. Combined w/ PMS you may indeed feel awful - my sympathies! Also, colds can invite bacterial infection and then need antibiotics. Flu is also viral, but hits more suddenly than a cold. See Dr if you think it may help w/ new symptoms. Read: http://www.webmd.com/cold-and-flu/cold-guide/flu-cold-symptoms?page=1