So, for a while I haven't been able to play for more than 2 minutes or so without fretting hand pain. Got a new guitar after not playing for ages, same problem. My techniques hasn't really changed since before this firt happened, and I've looked up techniques for how this should be done, but still
Ok, first: go see some kind of health professional, recurring pain is a cause for concern if you ask me.

Second: examine your posture very carefully; look for any joints that are at angles, you should be aiming to keep your wrists at least as close to straight as possible as much of the time as you can.
R.I.P. My Signature. Lost to us in the great Signature Massacre of 2014.

Quote by Master Foo
“A man who mistakes secrets for knowledge is like a man who, seeking light, hugs a candle so closely that he smothers it and burns his hand.”

I tried again today and a lot better, virtually no pain. No proper sessions, just quick bits of play. Whenever I felt the tension coming on, I'd tweak my position and that would fix it. Trying to follow proper technique (i.e. wrist straight, back straight, elbow out when playing lower down, finger tip play only and NOT pushing too hard), unfortunately breaking years of bad habit which I guess caught up with me