Some stupid questions if I may.

1. What freq did you use on 20m?

2. Did you cut/prune the antenna for that frequency?

3. What is the resonant frequency of the antenna as it stands now?

4. Did you hook up your analyzer and see what its telling you about swr/Z at the operating frequency of question?

It sounds like the transmitter may have folded back. Just check and see what the antenna is telling you. Others should chime in shortly