Elbow aches when I squeeze the racquet handle firmly and extend my arm.
I've been playing more recently. I also feel some pain/discomfort on overhead shots. Any suggestions about possible cause and remedy?
Not enough description. The elbow has anterior/posterior/medial/lateral aspects and the joint itself. Where is the pain?.
Apologies, yes, too little information. The pain is lateral I think, so if I place my arm against the wall with the back of my hand to the wall, the pain is where the elbow touches the wall.
I did a lot of stretching before and after playing yesterday, I have a book on stretching so followed advice there, also rubbing the affected area, and it feels a lot better today.
Internet diagnosis is a shot in the dark, but...
There's a good chance you have tennis elbow (lateral epicondylitis), which is a common injury among badminton players.
An excellent treatment for this is the Tyler Twist exercise, using a Theraband Flexbar. And of course, rest helps too!