Sharp and sore pain in WT extract site.

Hi, I removed my upper right wisdom tooth 23 days back. It was an erupted tooth and had no stitches. OMFS said no stitches required. I didn't use that side at all to chew food. Having food and drinks at normal temperature only. Went for follow up last week. He said extraction site is healed. Yesterday and today I tried to eat food on that side. I tried to have foods which is little hot. Suddenly I felt sharp pain on the extraction site. Just once for a second. Then its just sore. I didn't use that side to eat. Today also I tried some mild hot lunch on that side. It was very sore in that extraction site. Is this normal? Do I need to stop eating on that side? Do I need to eat only room temperature foods? I saw the extraction site and it's white in color with some dark red spots in the center. Is this normal to have sore pain after 20 days on that extraction site? How long does it take to get back to normal? I am having some lower jaw pain and swelling issues going on for 2 months.