Why is the heat on my Toyota Camry not working?

What is your question?

I have a 2007 Toyota Camry and the temperature gauge will go almost to hot after driving it for about 2-3 minutes every time and then go back down to right below the middle and stay there for a while. Then it goes up near hot again and then comes back down within about five seconds and stays in the middle. My check engine light has not come on at all. Also, the heater just stopped working in my car. The fan works fine, but just blows out cold air. Is it a bad thermostat causing both of these problems?

What makes this problem better or worse?

Nothing - it happens every day

How long has your 2007 Toyota Camry had this problem?

One week