I've been playing the piano for more than 10 years (a bit of an on/off situation though). During the last months, after playing for a couple of minutes, the right thumb and area surrounding it (indicated in the pics - not my hands

) starts to tire and feel uncomfortable. If I keep up, pain sets it and a feeling that sth. really bad will happen...
I stop of course and can resume playing after a few hours, but a feel of weight and weakness always stays there. I try to play relaxed, avoiding possibly dangerous movements (ie. excessive thumb-under), even stopped playing for ~20 days, but nothing.
As you can imagine, it is very frustrating and I'd really appreciate any feedback...
Thanks for reading this.
