Miranda- It would be my guess that your symptoms might be related to the texting.  Perhaps you should try to text a little less, and see if that makes a difference; if it does, then that might be the reason!  I know that "The Doctors" featured a segment about "text neck" on one of their shows, and I think that they might have also covered problems with hands and fingers, too.  If I remember correctly, issues similar to carpal (sp?) tunnel syndrome, as well as tendonitis, are being experienced by people who text quite a bit. 

Maybe, if you hold your "texting" device right before you text, you only move your two thumbs and rest of fingers stay at rest.  Unlike playing an musical instruments where you use all of your fingers, texting only focuses on your thumbs.  Probably eliminate unnecessary texts will be good idea.  But here is the good news about using your fingers and hands:

As we start to use all our fingers and hands, our brain start to gets active.  As we age, we have to find simple and joyful activities that uses all our fingers and hands to keep our brain young.

Yohan