When i have the cold , i get really huge cold sores .why? my lip looks scary

It can appear so..: Cold sores often appear with just slightly yellowish fluid (plasma-like) but larger ones can look like puss-filled lesion and unsightly. It is a reactivation of the herpes virus that you acquired in the past--they live/stay dormant inside the nerve and often come back in same spot. Consult doc. These are treatable during acute attack, as well as preventive medication regimen. Good luck.