Bibi, who is this second surgeon you are going to see and where does he practice? With your history, you need a specialist and I'd like to take a look to ensure this person has the qualifications you need.
If you had an infection in your knee, a boil on your stomach would not be an indicator. You'd have pain, heat and redness in your knee. Sometimes the incision opens up and drainage starts. You'd likely be running a fever.
Please try not to jump to conclusions when you read others' stories. Self diagnosis (even for those of us who know a thing or two about joints!) is usually not a good idea.