It is recommended you wait approximately 48 hours after wisdom teeth extraction prior to eating foods such as Pizza and sandwiches. It is preferred that you stick to foods like jello, ice cream, mashed potatos, soup and juices. After the 48 hours has passed and you start to consume more solid foods, I recommend you gently irrigate the extractrion sites with saline rinse (salt water) after each meal to keep the area clean. This prevents infections from developing. Your Oral Surgeon or Dentist will give you a syringe to help you with the oral hygiene maintenence at home.
As far as your concern regarding dislodging the clot. This is a very valid concern. Breaking the clot can lead to a dry socket which can be very painful and need a visit to your dentists office so that they can apply a dressing to help sooth the area and help in developing a new clot. The way you can avoid breaking the clot is by avoiding actions which require sucking and spitting, such as: sucking drinks through a straw and smoking and try to avoid spitting as well. By avoiding these actions for the first 48 hours, you greatly reduce the risk of breaking the clot and developing a dry socket.
With regards to the irritating stitches, the solution is simple. Just go to your dentist or oral surgeon and have them trim the longer pieces of the stitches that are rubbing against your cheek. This will make it more comfortable.
Good luck!!
Dr. Parnaz Aurasteh