We need help , im not a mechanic and don't know anyone that is . all i have is google and im not finding the answers .

We have a 1999 Toyota Camry . Its a good running car but , the last month or so the Temperature Gauge has been going up and down from middle of the gauge to above the red mark . The last week or so it stays on Red but its not overheating . I constantly stop and pull over to check if its over heating and its not . The car runs fine but the Gauge still stays on red .

Yesterday we had the the Temperature Gauge sensor and the Thermostat changed and the Gauge still stays hot .

Im lost as to what it could be because the car seems fine but the gauge floats near hot or on hot all the time now .

Thank you ahead of time for any information .